I suspect that Apple's intentions are moving more into making the laptop portable again. I've used the bigger, high-er end laptops, and, while they can be used on battery, on your lap, it's normally about as comfortable as using a netbook to write a novel, possible, but not something that you'd do willingly anytime soon.
The role that is occupied my most other desktop replacement laptops (machines that are portable, but need a power socket and a desk to use), could actually, quite happily be filled by an iMac (what do you need? power, wireless keyboard, wireless mouse?), the MacBook Pros are intended for people who will actually want to be using them where desktops are impossible (trains, planes, on the sofa) and, in these circumstances, you wouldn't want that uber power for film editing or photoshop, because it's not really the locale to do it in.
What Apple are trying to do is make devices that fill the gaps where needed:
iPod - largely unseen, simple controls, mainly for music playback.
iPhone - Will make phone calls, but mainly for those times you need to get something done URGENTLY (email, a quick web search).
iPad - More typable, used when you might actually need to take notes, or do something that would need a keyboard, but not the whole power of a laptop.
MB(P) - Out-and-about work. You can type out a document, or, in extreme cases, actually do video-stuffs, but it's not ideal for it.
iMac - Desk-hoppers. Transportable, easy set-up, gives you your workstation where you are.
Mac Pro - Static, powerful, powerhouse. Nuff said.
Now, you can't use photoshop on an iPad, and you could use a Mac Pro just for web-surfing, but it's a bit of a waste. Each device that they've got, has it's place. You will not need them all, but you will have to be realistic about the ones you do. You can buy a 17", top of the line MBP to do photoshop when you switch between offices, but it'll always be pushing the upper limits of the capability.
If you need something to do a job, make sure it'll do that job before you buy it! If your needs change, you have to accept that the device might have to be changed too.