Would probably need to negotiate for a huge amount of dedicated priority bandwidth, but latency shouldn't actually be that bad.
* while there could, in principle, be no extra infra in the last 200 km vertically, that means someone on the ground is talking directly to GEO. As per similar discussion about big PV space stations beaming power to the ground, your minimum ground spot size for a transmitter this big and this far away is still tens of km, which limits the other parts of your overall system design.