It most certainly will.
And I can see it changing the PS4 to be even more of a Xbox clone, or similar or whatever you want to say. Sure 1st party sony will still produce their games, but I'm guessing most all 3rd party Japanese games that Sony was getting will go to Switch. All those anime style, jrpgs, visual novels, ect will abandon ps4.
The userbase size will just be too big to ignore on Switch for Japanese gamers, and not to mention the less powerful hardware will also be more appealing. Companies will be able to release games that look like Octopath, or other styles that you would see like on a 3DS and you wn't have the PS4 graphics crowd ignoring it cause it looks "indie" The sheer number of games will just be so much more. Square Enix will release 1 Final Fantasy 7 remake in the span of a half a dozen RPG's that look like Bravely Default/Octopath/I am Setsuna for the Switch.
Graphics have killed many genres. Or dwindled their size at least. The Switch is not only a hybrid in handheld/home console, but also in graphics. Their top games Zelda/Splatoon/Mario and stuff sit perfectly beside games like Pokémon Sun/Octopath/Monster Hunter. Because of the nature of Portable, poeople won't be expecting every game to be pushing cutting edge graphics.