I'm getting your point but you are not understanding what I'm saying so I'll have to say it in a not very friendly way in order to make things more clear for you: you are simply wrong on all accounts due to a complete lack of knowledge. Nothing you say is even remotely close to how current and future technology works. You also fail to understand the inner workings of a computer and are thus unable to understand how a machine uses its battery and how you scale a system (either to more performance or to more battery life or to a thinner and lighter design). I'm trying to make you see that and I'm trying to get you to understand how it really works.
Again, in short: the MBA is not going to significantly increase in weight and size when you equip it with a retina display. The 13" MBP which is similar in size and weight proofs that because it has the retina display as well as more powerful hardware. Also, changing the display requires other components to be redesigned plus they'll use more up to date versions of it. Altogether this will lead to a machine staying exactly the same in size, weight, battery life and computing power. It just has a better display. The problem is the difference with the MBP. The MBA used to be a thin and light system, the MBP thick and heavy but powerful. The MBP is becoming thinner and lighter due to the current energy efficiency in hardware (which is ongoing, we are not at the end of the tunnel) and the MBA is becoming more powerful (also ongoing). The gap is getting smaller and smaller and that is a problem. The MB is simply a completely redesigned MBA. The only problem is that it requires hardware that isn't entirely ready yet, it needs to mature. That's why they can't replace the MBA just yet and also why they won't put a retina display in the MBA. And they'll probably stall it a bit because the MBA sells rather good.
You are also incorrect about displays. They too are becoming more energy efficient. CCFL has been replaced with LED and we are now using other types of panel technology such as IGZO. Due to technology like this the displays have also gotten thinner. There are also other technologies that greatly help reduce energy consumption too. FreeSync comes to mind as well as that nifty feature where the display isn't being refreshed if the image doesn't change (which can have quite a big impact on battery usage). I've replaced my displays with modern ones because of the big improvements in energy consumption. I managed to cut energy consumption by about 30% to even 50%. This is with displays from the last 5 years so we are seeing a 30 to 50% improvement over 5 years which is rather big. And no we are not at the end of the tunnel yet. The biggest hit on energy is still the backlight. The CPU/GPU combination driving that display is also getting more powerful per watt (in reality they are becoming more powerful and use less energy) which greatly helps (you don't need a power consuming dGPU to drive a retina display any more).
Shrinking hardware is done along the full line of hardware no matter if it is in the MB, MBA, MBP, iMac, Mac mini or Mac Pro. Xeon CPUs used to be for those large servers and workstations but now we have Xeons that can be put in notebooks. We now also have something called microservers which use CPUs like the Xeon E3. These are workstations the size of a NUC. We used to have several chips like a CPU, Northbridge, Southbridge and GPU. Now we have 1 chip that contains those previous 4. Next is Thunderbolt. Intel is working an integrating that into the CPU as well as USB3.1 (Gen 1+2) meaning one less chip. When it comes to memory we see new technology like stacking layers (aka 3D memory) as well as manufacturing these things on a smaller scale (CPUs too btw). This causes memory dimms and SSDs to hold more memory and thus have more capacity. That also means things become smaller when you stick with similar specs (which is exactly what Apple is doing). Apple has the new keyboard from the MB they can port over to their other models. So yes, there are a lot of things that are shrinking in size which allow computers to shrink as well. The MBP is like any other machine and thus no exception to the thinner, lighter hype we are currently in. So yes it can shrink, it will shrink and it will still stay Pro. The other thing is Thunderbolt. With that, even an MB becomes a Pro. That's where we are going.
Again, in short: the MBA is not going to significantly increase in weight and size when you equip it with a retina display. The 13" MBP which is similar in size and weight proofs that because it has the retina display as well as more powerful hardware. Also, changing the display requires other components to be redesigned plus they'll use more up to date versions of it. Altogether this will lead to a machine staying exactly the same in size, weight, battery life and computing power. It just has a better display. The problem is the difference with the MBP. The MBA used to be a thin and light system, the MBP thick and heavy but powerful. The MBP is becoming thinner and lighter due to the current energy efficiency in hardware (which is ongoing, we are not at the end of the tunnel) and the MBA is becoming more powerful (also ongoing). The gap is getting smaller and smaller and that is a problem. The MB is simply a completely redesigned MBA. The only problem is that it requires hardware that isn't entirely ready yet, it needs to mature. That's why they can't replace the MBA just yet and also why they won't put a retina display in the MBA. And they'll probably stall it a bit because the MBA sells rather good.
You are also incorrect about displays. They too are becoming more energy efficient. CCFL has been replaced with LED and we are now using other types of panel technology such as IGZO. Due to technology like this the displays have also gotten thinner. There are also other technologies that greatly help reduce energy consumption too. FreeSync comes to mind as well as that nifty feature where the display isn't being refreshed if the image doesn't change (which can have quite a big impact on battery usage). I've replaced my displays with modern ones because of the big improvements in energy consumption. I managed to cut energy consumption by about 30% to even 50%. This is with displays from the last 5 years so we are seeing a 30 to 50% improvement over 5 years which is rather big. And no we are not at the end of the tunnel yet. The biggest hit on energy is still the backlight. The CPU/GPU combination driving that display is also getting more powerful per watt (in reality they are becoming more powerful and use less energy) which greatly helps (you don't need a power consuming dGPU to drive a retina display any more).
Shrinking hardware is done along the full line of hardware no matter if it is in the MB, MBA, MBP, iMac, Mac mini or Mac Pro. Xeon CPUs used to be for those large servers and workstations but now we have Xeons that can be put in notebooks. We now also have something called microservers which use CPUs like the Xeon E3. These are workstations the size of a NUC. We used to have several chips like a CPU, Northbridge, Southbridge and GPU. Now we have 1 chip that contains those previous 4. Next is Thunderbolt. Intel is working an integrating that into the CPU as well as USB3.1 (Gen 1+2) meaning one less chip. When it comes to memory we see new technology like stacking layers (aka 3D memory) as well as manufacturing these things on a smaller scale (CPUs too btw). This causes memory dimms and SSDs to hold more memory and thus have more capacity. That also means things become smaller when you stick with similar specs (which is exactly what Apple is doing). Apple has the new keyboard from the MB they can port over to their other models. So yes, there are a lot of things that are shrinking in size which allow computers to shrink as well. The MBP is like any other machine and thus no exception to the thinner, lighter hype we are currently in. So yes it can shrink, it will shrink and it will still stay Pro. The other thing is Thunderbolt. With that, even an MB becomes a Pro. That's where we are going.