And do you think that Sony will be so arrogant allowing Nintendo handhelds to keep Monster Hunter for long? Nintendo's new handheld already have working Pokemon games now they have Monster Hunter as well. That's too scary for Sony and they will try to change that.
I'm not telling that MH4 is not going to be released only for 3DS in the beggining. But no way Sony will wait 2-3 years, they can't afford that.
/../