I think we'd be fools not to expect a rerelease of P5 at some point. I already figured a "Persona 5 The Golden," so to speak, would happen eventually.
I personally don't really want one to happen though, unless they have it also include all of the DLC and patches that vanilla P5 will end up receiving on-disc, including the Japanese voices and then they don't release any more DLC/patches afterwards, so that it can act as a final, definitive copy of P5.
Well, remember that the game isn't new. We don't have it stateside yet, but it's been out in Japan since September. Tons of people have already played it, both overseas and through importing and that poll is based in Japan too, so its target audience has already finished the game months ago. Even Lotus Juice kept talking about P5 on Twitter back in September too, poking fun at himself for putting all work on his next album on hold as he kept getting sucked into P5 lol.
As for getting HD reissues of the older games, I think that's fine for P1 and P2 (though the P2 remaster should include both episodes in one package), as well as P3, if it's essentially P3FES with the added bonuses of P3P ported in. It's completely unnecessary for P4 though. P4G is already a definitive version of the game and is already HD-ified enough. There's no reason to touch that game again.
Lastly, for more spinoff games, I admit that I'd personally like to see a P3D made, with some improvements of P4D's faults, but overall I'd prefer that they stop milking this franchise to hell and back.