I don't think this is necessarily an area they have a full say in though. The PSP market's all but gone with digital being one of the only practical ways to release, and PC's in some ways worse for anything that isn't a big blockbuster or at least notable enough, even Dark Souls went straight to DD in the US (though that could just be Namco Bandai sucking). HOWEVER, to a degree you're leaping to conclusions here: while it might not be too practical to release new PSP games by the time they can get done with Trails in the Sky 2, it's possible that they'd still put out a limited UMD release. The bigger reason getting a PSN option out there was simply so that it'd be safer to translate the game and get it out there, they don't have to worry about people needing to find the UMD as they ONLY way to play it, or keeping around a PSP with a working UMD drive in order to play it, they can get the (admittedly probably small) PSP GO base, along with the Vita base.
