Playdate will definitely make it to market in some form. Panic have some experience in game publishing already with Firewatch and recently Untitled Goose Game, and Teenage Engineering are a respected brand in hardware synthesizers. Heck, their Pocket Operators are basically Game Boys with little sprite animations and everything.
Whether it'll be good... Eh, using those Pocket Operators is pretty unintuitive if you ask me, but obviously Playdate will be much simpler. It's got a fun design going for it, I guess. I'm not biting at that price, but I wish the creators well - provided they stop being idiots when they're the ones who named their device after a literal already existing word.