If the rumors are true and the new MacBooks are to sport an Nvidia chip, why would you buy a Mini? All you have to do is plug a monitor into your MacBook and your have a desktop machine that would be way better than the Mini. You'd have a great desktop and a portable for on the go. If they put a dedicated graphics card in the MacBook then I think the Mini is dead. I see no reason to put a dedicated graphics card in the Mini. They'd cannibalize their iMac/MacBook sales.
I think the Mini will just go away with no mention by Apple. Kind of like the iPod Hi-Fi. Now you see it, now you don't. The Mini was supposed to be a super cheap Mac for people that wanted to make the switch but didn't want to invest a grand in a new platform that they may not like. So it was a way of getting PC users to switch for as little cash as possible. And sure, you could get your feet wet for $499. That's a good price. But then they went Intel and the price went up to $599. Now add an Nvidia card, $699? Suddenly, that "under $500 Mac" isn't so cheap any more. In fact, it's not that much cheaper than the supposed new $800 MacBook. And we all know Apple loves selling MacBooks.