Depends on what deal they have with Nintendo- I imagine they are contributing an awful lot of the marketing expenses overseas. Seeing as Nintendo are likely to release another handheld and Sony aren't, and they don't want to split the player base, perhaps it makes more sense to continue to release a portable version of MH5 on Nintendo's next handheld, and then follow that up with a console/handheld multiplat version of the later expanded edition for the west. A bit like Toukiden, perhaps. Anything they can do to help people play together across WiiU/3DS or PS4/Vita would be cool too, letting console and handheld players hunt together would be in the interest of the franchise long term.
It's interesting to see Monster Hunter gradually getting it's teeth into the west. It's been limping after that prize like a wounded Great Jaggi for so long