This thought process still blows my mind. My first gen iPad (64 3G) still holds up just as well. It still doesn't even seem time to upgrade from that little device, I can't imagine selling the third gen revision in just a year or two.
for a lot of people, a first gen ipad like what you have will still be OK.
But a lot of other people, it’s not. Might come down to something like a FaceTime camera or (in my case) support for more ambitious media apps like iMovie, iPhoto, etc.
edit:
Very early but this had me thinking.
What sort of things can we expect from iPad 4 next year? I remember last year when iPad 2 released, a lot of people could see what they'd add with the 3.
the easy one is a faster CPU.
beyond that, it gets tougher. maybe they can reduce weight. but if they do it, what do they change? make the back material something lighter? make the front glass thinner? make the battery smaller?
making it thinner seems like something they’ll try to do again. might be easier than making it lighter.
the screen may have better colour and black levels incoming years but the resolution bump some of us wanted isn’t going to get bumped again so that’s set for a long time.
beyond that you need to think about more esoteric stuff like that haptic feedback for simulating surface texture. that seems like an interesting demo feature. not sure if it’s a great long term thing.