MK games in general has always "been dead" online. Most play against friends online or just locally. There will be matches, even on MKvsDCU you can find people, but nothing bigRuns great on my 980Ti, 4K with everything maxed.
Tempted, but if there's no crossplay, what's the point? It'll be dead.
Throwing PS4 people will only throw like 100 people per hour.