Well basicly i am guessing that they arent making them since there market is to the Consumers,
If they would make a SLS or SLA printer this would be around 2-4k, wich most basic users wont buy as its to expensive,
I am guessing thats why they didnt do the effort yet,
But they might in the future of course,

Like you said extrusion printers wont be forever, at all, and the technique is simply hitting its limit as Extrsion type printers go.