I really hope the iPad 3 continues to be supported. I know it is getting slow but I do not mind that for what I use it for. I am not prepared to start thinking of my iPad as outdated the time has gone just too quick. Even begging for one more generation is silly, but I know as soon as the software is out of date apps will start working like crap. I do not feel I have gotten enough values worth from my iPad to feel "sold" on running out to buy a replacement. This will likely just make me iPadless and a little bitter.
Just my thoughts. I agree with the rationale that ti won't be supported, but it will frustrate me when it becomes official.
If you got your 3rd gen iPad when it was still being sold, then that means that you'd get 4 years out of that device. That's plenty of time. It's basically an iPad 2. It may have slightly better hardware, but that better hardware only exists to compensate for the Retina display so that the 3rd gen iPad wouldn't slow down significantly. But it's among the slowest iPads in retrospect 4 years, and 5 iOS releases is plenty of time for your iPad to get the latest software updates.