If they don't overprice it, it can very well be a good seller, especially since it's the holiday season. Never to late to jump on the bandwagon, as they say. It's have been even better had it been backward compatible with PS2 games, imo, though. Still, this'll definitely give Nintendo's Wii U (which I think is really dumb, honestly) some competition.
As for if it's a sign of PS4, no. Had Vita not come out, I'd have said maybe, but I'm not sure, honestly.