If you go to the Musketeer's Guild or even the Thundersticks shop in Limsa you can clearly see Rifles all over the place. Clearly if they weren't going to be a possible weapon they wouldn't have put them up all over.

I'm going to be extremely pissed if Gunblades and Gunlances are NPC only. It's like a giant "Hey we know you want this so F U!" SE knows their audience and they know they love gun hybrid weapons. It would just be too mean.