Maybe. But I have a first generation iPhone. It cost $599. For everybody waiting for a bigger tablet, thinking that it'll cost $600, please keep that in mind. My iPhone cost $600. The new ones reportedly still do, only their price has been buried beneath the AT&T subsidy.
If you're wanting a tablet with a bigger screen at the same price point, it'll have to be at the expense of some other features, and I can't imagine what that would be. If anything, we'll want the bigger screen PLUS a lot of features. How is it gonna come in at $600. (And of course, if it ever did, there would be an outcry because the week before a rumor would spread that it was going to be $400, but that's another issue).
Don't forget that the $600 iPhone, while not traditionally subsidized, had profit sharing backend subsidy.
Apple might sell such a device for $900 and then sell it through AT&T with a $60/month data plan with a 24-month contract. This is how they et al. currently sell their $300 3G cards to consumers.