This is a highly optimistic and almost certainly incorrect prediction.
Smartphone gaming is the biggest segment of the gaming market presently, but it exists entirely outside and independently of the console and PC gaming market. However, it may become a ground for mainstream gaming, according to the NPD Group, with the launch of 5G networks.
The NPD Group made this prediction in the newest edition of their newsletter (via Twinfinite); according to their predictions, as 5G catches on, and with the launch of streaming services such as xCloud and Stadia, smartphones will play host to console-quality games and multiplayer titles. According to the NPD Group, 4G and LTE’s limited connectivity has stopped this from happening thus far, but it will change with 5G.
There are, in my opinion, multiple flaws in this reasoning: a) 5G is built on entirely new infrastructure that largely doesn’t exist right now, and is unlikely to be widespread by 2020; b) mainstream 5G hendsets are unlikely to exist in large numbers by 2020; c) 5G has its own connectivity problems (mostly extremely short wavelengths leading to higher potential for interruptions and disconnections by things as simple as walls); d) 5G coverage is unlikely to be widespread when even LTE and 4G coverage isn’t; e) data caps are unlikely to magically go away just because 5G exists; and finally, f) you’re still streaming a game, and smartphones still are touch screen only.
So I disagree with the NPD Group here—but who knows, they’re the analysts, maybe I’ll be wrong.