Did you not hear the part about the Switch getting an exclusive Fire Emblem gaming in 2018? Why can't both of them coexist. One of my IRL friend's actually thought Nintendo was going to drop 3DS support and was getting upset. For some people the battery life and form factor is enough of a reason for Nintendo to continue pushing the 3DS for another 2-3 years and let it die slowly.
Secondly, the Warriors franchise is not a system seller. Personally I can't stand them. The combat is just repetitive rather than skill based, and the animations are horrendous. The level design is flat and boring and most of the enemies die at the flick of the fingers. I'm a huge Fire Emblem fan and I might pass on this unless I hear good things. As a huge Zelda fan I hated Hyrule Warriors with a passion. I wanted the main story to be over with and I felt it was waaay too long. It should have ended before you took control of Ganondorf despite he was actually fun to play as. The adventure mode bit was really cool but I was bored after doing a 5 or 6 of the missions. It was all just the same stuff with a different twist. I'll admit that the game has a lot of content but it's just not for me. I got bored way too fast with it and it was just a mindless game that did not engage me in any shape or form. I'll admit that I don't understand the appeal of this series and I know very few people personally that enjoyed them, but obviously they do something right to get sequels and I know they are hugely successful in Japan.
TL;DR: They will both co-exist just fine, and the Warrior's franchise isn't mainstream enough to be considered a huge system seller. They would just be kicking themselves in the foot by not letting it be accessible. Some people will prefer that game as pure handheld title, and others prefer it on a TV. This is the right way to go about things.
