@
Delwis, I'm going to second @
Scooty Puff Jr.
It seems to me pointless (just my thought!) to go to mechanical discs of any kind given that you have perfectly good/nice/really quite decent hydraulics stock on your bike: those Tektro 310s.
Sure, something from TRP or Shimano would be nice. If you did want to change the brakes now, and do want to stick with flat-mount calipers, I'd be tempted to ascertain whether a set of Ultegra or Dura Ace level calipers (flat mount) could be mated to XT or XTR levers, and whether you could purchase the calipers and levers separately.
If so, then there's your solution. Otherwise, I'd be inclined to wait for a year or two: I've no doubt that flat-bar flat-mount hydraulic brakesets will become more easily available aftermarket as time goes on.
Just some thoughts!