I’m assuming that running multiple 5-6k monitors will still require multiple cables/ports though. One thunderbolt port per monitor.

I’m still waiting for the day we can hook 2 5k monitors + peripherals up to a thunderbolt dock and then hook that up to a MacBook using a single cable.

MST is not supported and won't be supported, that's been Apple policy for some time now. Only Thunderbolt tunneling is supported for multiple screens on one output (which logically provides separate DP outputs, no MST)