Ummmm shared Universe is what comicbooks are all about. Marvel is doing it RIGHT. Perhaps one day the animated series'(?es) will also be cannon with the MCU and even more live action shows can spin off. It's the right thing I tell ya. So what is DC gonna do? Just completely ignore the Green Lantern movie as if it never happened? Nolanverse, GL failverse, now MoSverse. Yeah. They should really start to focus.
Unless they are gonna have some heavy hitters like Darkseid who can actually make a Kryptonian feel it, this Supergirl show is gonna get real boring real quick... Although they did make Smallville work for quite a while.