"mobile is maturing and its growth is slowing"...yes, somewhat on the hardware side. There are still annual sales of maybe 1 billion smartphones a year...so that's a pretty big market.

I think that there's still ENORMOUS potential for mobile apps and mobile-driven services. There's huge opportunity for new services e.g. Uber. I think just about every large web/desktop property faces a significant threat from a mobile app e.g. craigslist, match.com (they luckily own tinder), flickr (wait, already gone to Instragam), AIM/Yahoo Messenger (gone thanks to Whatsapp), etc...