It is a bit disconcerting that the first iPad is being dropped. If there aren't many major UI changes I will be extremely concerned.
The main reason is that the iPad should have a life span of more than two years. With a phone, you get a subsidy every two years as your contract expires. Buying an iPad is more akin to buying a laptop, as you buy it outright.
Hopefully the falloff window is extended over the years, as the iPad 2 is pretty similar in performance to the new iPad. This drop was probably due to 256MB of RAM.