I'm sure it'll sell like crazy... but I can't figure out why except "because GLOCK"
Seriously, if you wanted a single stack, striker fired, sub-compact 9mm. It's not like there has been a shortage of fine firearms to choose from in the past several years. M&P Shield, Springfield XDs, Walther PPS, Ruger LC9s and Kahr PM9 all come to mind off the top of my head, I'm sure there are others. Also if you open your mind to hammer-fired then there are many more options.
But even though they are very late to the party, I'm sure Glock will outsell all of them for no good reason except the blind unshakeable devotion Glock fans seem to have.
I guess I just don't "get it" when it comes to Glocks. Personally I feel there are so many other options out there with the same proven reliability, yet with much better ergonomics and triggers.