I'm feeling less angsty about this with the more-than-likely specs being announced, and seeing more of an upgrade to existing components than completely new bits of hardware such as an extra GPU etc.
I suspect it'll basically offer the difference of something like, say, a PC game's default medium and high settings, with the latter offering equivalent to a better AA solution (or 4K) and a small handful of extra little XMB options like KennyLinder suggested such as 60fps capture or something.
Doesn't even sound like the upgrade would smooth out the framerate of a game that would otherwise be poorly optimised to run on the vanilla PS4. If it does though, especially for a game like Bloodborne, to give it a flat 30, I might consider upgrading. But only if I'm not significantly out of pocket.