Didn't the Persona team make P4G with some of the people from SMT: Strange Journey? That is what I can gather :l (at least some other people from the SMT series helped make Golden, as
wasn't made by the Persona team).
I think after Persona 5, they will make a Persona 6; remember how fast Persona 4 came out after Persona 3 (P3 was finished late 06 in Japan but due to some pre-order issues, the US version got delayed into the Summer 07, then Persona 4 came out sometime in 08 with the FES version of Persona 3). They are fast workers from the sounds of things, so they will most likely make Persona 6 come to PS4/PS3 (at that point it should be 2017, as they took 2 years to make P4, so they would have to put the game on some next-gen platform to get some more sales).
As for why many think their will be a Persona 3 Remaster for Vita? Well, it just makes a lot of since. Sony may give two shits about the Vita in America, but the Vita is doing better then the PS4 in Japan, and JRPG's there sell great on Vita (P4G pushed ALOT of Vita's to be sold and a more recent example was how Freedom Wars did quite well in Japan, as did God Eater 2 I think....). Altus would be smart to bring P3 to Vita to take advantage of the series growing popluatary (and the game is old enough to warrant another remaster; FES came out the same year P4 PS2 did while P3P came out in 2008).
Will it come to the US? Well, Altus knows how many love Golden on their Vita's and it did do well here (not to mention they aren't picky with sales; they have very modest expectations for their games sales wise, an example was them making a cake to celebrate Catheren selling I think 50k copies? I'm not sure the exact amount but it wasn't a huge hit, so them celebrating modest sales was very noble of them

). The Vita may not being doing well in the US (...at all sadly X(), but, that doesn't mean publishers like Altus would just avoid the system; if they think it's worth it, the game will come here (if it is made).
That's just my two since there

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