Well, don't fret. First of all, nobody has bought an iPad with 3G yet. Secondly, people aren't going to use those near as much as iPhones. I'm assuming that most people were replacing simple phones with iPhones, and that's something most of us carry all of the time. I don't forsee EVERYBODY always having an iPad. Just the fact that it won't fit in your pocket keeps that from happening.
Personally, I think I'd rather have 32GB of storage and $30 than a 3G radio. I'm already getting killed on my phone bill, so I couldn't justify that. If I got to a point where I could afford the extra $15/month, I would probably have a new job and could afford a new iPad.
So I personally think I'll get one sometime soon, but I don't know. I'm kinda letting the early adopters test it out and then maybe I can discover if any killer app for it exists. I'm really interested in one as an ebook reader and perhaps news site reader. I put off getting a Kindle to see what Apple would do. Well, for about twice the price, I get pretty much a computer. Sign me up.