Overwatch’s director Jeff Kaplan has a penchant for being very open with the game’s community from the start. He might not say everything you want him to (especially in regards to balancing), but he typically fields questions all over, from official venues like BlizzCon, to Battle.net’s forums, to Reddit.
This time when asked about being “up to the challenge” of putting out a Switch port, Kaplan replied “I’m loving the Switch! My second favorite gaming platform of all time is the 3DS. Getting OW on the Switch is very challenging for us. But we’re always open minded about exploring possible platforms.”
It’s PR speak for sure, but it’s a recent development in the saga of “will Blizzard put anything on a Nintendo platform anytime soon.” He didn’t outright deny it, but since it’s not actively in development it may not happen anytime soon. I bet Blizzard is already having a hell of a time balancing three versions of the game on PC, PS4, and Xbox One (especially since consoles are tweaked differently than PC).