I'm not sure about thinner, but I do think lighter if only marginally. With the thought of the bezel getting thinner on the sides, that makes the device smaller. So if it is smaller it should weigh less. But I don't think will be back down to iPad 2 level, as it still has to have a battery that powers a retina display.
Definitely, its going to be thinner, as we have seen from the case leaks.
But what's the reason behind thinking that it wont be lighter than the ipad 2. Looking back at history, Apple has always tried to make their devices thinner and lighter, with some exceptions being the ipad 3 & 4. Even then, the ipad 3 & 4 is marginally lighter than the original ipad.
Now coming back to the main point, the weight is definitely heading downwards.The overall dimensions of the device will be shrunk ( yes, I agree thinner bezels is one of the main elements of that). That itself will help reduce the weight. In this case, let's b really pessimistic and assume just a 50g reduction is all they get. Next, its sure that they are going to utilise the GF/2 manufacturing process to the ipad 5 as well. Let's again, undervalue the weight reduction and just put in a minor 10g. Last but not least, we have learnt that the A6X SoC is now mostly going to move on to a 28nm process from a 32nm.With that and some minor tweaks, let's presume they save about 5g. Now the total is 70g.
(I am only referring to Wi-fi models here)
ipad 1 - 680
ipad 2 - 600
ipad 3/4 - 652
ipad 5 - 587g (logically anticipated with these scenarios?)
Here, I haven't event assumed that Apple is going to utilise IGZO, and therefore would require a thinner / lighter glass, and perhaps even move onto a single LED unit. Similarly, IGZO should help reduce power consumption massively ( claims are there upto 90%, but I would like to think of it as just a 50% reduction in real life). If that is the case, you don't require such a massive battery and my previous posts would tell you, a 1/3 reduction in the battery size is the logical way to press forward. I haven't even considered a smaller / thinner battery in the above scenario, while technically speaking it shld b because the overall device is thinner and smaller, and therefore it is guaranteed they are making the battery thinner /lighter to. If you consider the, the weight should go down even further from what I mentioned above.
I don't care how heavy it is, I just don't want another massive battery.
Well, according to the case leaks, and rumours from the industry, it looks like the battery size is definitely coming down, and thereby helping reduce long charging time. Reduced weight is given then. Let's keep our fingers crossed and see how successfully they implemented our wishes.