Definitely, the iPad should become a standalone device. That doesn't mean it has to be a full-fledged computer running OSX.
Here's the thing: a lot of people don't actually need a full-fledged computer at all, ever. What do most people do on a personal computer? Check email, surf the web, check weather/news/sports scores/movie times, shop, play games, watch videos, and listen to music. You can do all those things on an iPad, and for that matter, you can do those things on a smartphone. I have many friends who rarely use their computer anymore because their phone is their go-to device.
I would wager 95% of people never use their computers to full capability. Most folks never create fancy websites, do pro-level video or photo editing, or write their own software. Of course the iPad is a fine adjunct device for those who really do use computers for heavy lifting. But it's also a perfect standalone solution for people who just want the fun and convenience that computers were always supposed to provide but never did until now. Apple should realize this. I think they already do.