That HTTP API is backed by etcd which uses Raft and that is where running over a large area is more likely to cause problems. One approach would be to keep the etcd instances in one region (and probably also co-locate the scheduler, controller manager there), while having far-flung worker nodes. This creates a risk of losing the control plane but in most cases services would keep running (but would be unable to react to any further issues until the control plane recovers).
You would also want to carefully design your workloads with topology constraints and region-specific services to avoid high application layer latencies though.
Overall it's a fun thought experiment. In practical terms I think cross-datacenter in a small geographic area would work fine but I probably wouldn't want to run a single worldwide cluster, both for the reasons above and for other scaling reasons.