Guacamelee! 2 was originally announced exclusively for the PlayStation 4 last year, back during Paris Games Week. However, it looks like said exclusivity won’t be true exclusivity—at best, just console exclusivity (for now). As ResetEra has noted, DrinkBox Studios has put up a page for the game on Steam as well, which is pretty clear indication that the title will be launching on PC, too.
The original Guacamelee! launched on PS4, PS Vita, Xbox One, Wii U, and PC—so fans of that game on other platforms can probably rest assured knowing that the sequel, too, will eventually probably come to the other platforms (especially since very few indie games ever actually maintain true exclusivity for long).
Until that happens, you can either play the original (brilliant) game again, or you can grab the sequel for yourself when it comes out for PS4 and PC, presumably some time later this year.