Ah, I also hoping it.
More feature also nice. More event (so your shinki also have some event with other shinki in your possession), viewing room (where you see your shinki hanging out and doing some random thing with each other), mission mode (though right now the only mission in my mind is going HoiHoi mode AKA pest control), no hammer space weapon (so you can see your shinki carrying her weapon) and lots more.
But the main point of playing busou shinki is to choose your most beloved shinki, finish story mode with her (then do for the others too), customizing her to your taste and playing style then go showing her off (or kicking other people shinki). In this one, psp have the advantage that you can do that anywhere, anytime, anyhow.
Even till now, I am still playing and customizing my altlene trying different parts, skills and weaponry.
Well, the possibility is not zero since busou shinki seems to be quite famous in japan there. Hopefully, the number of fans and demand is enough for encouraging Konami to make PS3 version.