Is there still a market for these very expensive workstations when you can get much more compute from the cloud?
Yes, because a lot of media people are scared away from the thought of putting together their own machine (and a lot of them also depend on Mac OS)
When we need to transfer raw video footage between offices, we still ship drives by mail most of the time.
(1) A lot of independent video people spend their time getting better at video stuff rather than learning the sysops stuff they'd need to set up or maintain something like that.
(2) Latency!
No, many businesses are a bit more clever than that.