In many countries in Europe, WhatsApp is just about ubiquitous, and used by the average guy way more often than email.
The same (from what I understand) for WeChat in China.
Yes, if you need to communicate outside of your local circle of family and friends, e-mail is still king (for business communication for example, no contest), but how often does the average guy does it?
My brother/sister/mom/friends might use the e-mail once or twice per day, while they would use IM on mobile dozens of times per day.
When you see people on public tranport or on the street writing on their mobile, what do you think they are doing?
Most of the time they are using some kind of IM, not writing an email.
iMessage is the solidified IM platform I see most, as if you have an iPhone, you have iMessage.
The addicts will still get their hit, but much as bad money chases out good money, its too expensive and politically sensitive to have humans generate that attention / interruption rush, so have machines spam the hell out of us.
Besides, TV is dying, nobody watches that stuff anymore, and all those "push media" people need work.
Expect life in the 2020s to be filled with a lot more interruption, mostly machine generated.
Some interesting predictions: going to run into problems with work/life balance because of merging too close and spam explosion, such that even cognitively successful people are going to be much less well informed at work in the future than now due to sheer spam volume. Another novelty is we're in the last decade of the voice telephone call, in the death of the voice phone call era there will be bot armies in the cloud calling you dozens of times per day until you disconnect your voice call service. My guess is federated social media will have to rise when legacy hyper-centralized social media becomes pure propaganda and advertising to the point of being unusable. Possibly the same social factors that led to TV regulation of commercials back when people used to watch TV, might be reimplemented for the internet in a peculiar fashion. It'll be a major social status symbol to be interrupted all the time, much like follower counts used to be a big deal, of course cool people will spend all their time holding their phone to their face, swiping away meaningless notifications.
Personally, I deleted my Facebook account and switched to Instagram to keep track of friends with... that freed up a lot of mornings.