Hopefully PS3.
Actually I'd say it's most likely to go PS3 or PS3/xbox360, the port for overseas.
There is a good market for a JRPG on those anyway, and a lot less competition than on the PSP. A PSP release will also amount to close to nothing in the west... on the HD platforms there's even some chance for decent sales in Europe.
In all honesty though I hope they'll make it more of a beautiful game rather than overly detailed and consequently with a high budget.