Anyone that thought Monster Hunter exclusivity would go to the PS4 has no experience with how the Japanese market, Monster Hunter, or basic economics work. Monster Hunter is a massive Japanese franchise, and it got that way because it's portable. Monster Hunter starter off as a PS2 franchise, where it performed middling at best. Once it moved to the PSP, however, its popularity skyrocketed. Since then, handheld Monster Hunter has gotten so big in Japan that there have been resorts specifically for players to get together and play. The plays don't want to give up portability, and Capcom doesn't want to greatly increase production costs.
The Japanese home console market is dead, and making Monster Hunter a PS4 exclusive would be suicide for the series.