That would be an interesting thing for the video production industry. Basically the entire market is divided between "professional" equipment, in which SDI continues to dominate (with some movement towards SMPTE 2110 aka IP), and "amateur" equipment which is all HDMI - with very few products on the boundary and supporting both connectors.
Consumer grade digital cameras have only recently (10 years, maybe less) started being able to output the live video feed over HDMI. Before that, believe me or not I've stumbled upon MANY camera models from 2013 or before that had an HDMI port, but all it was good for was displaying pictures from the memory card on a TV.
It would certainly make life easier in a lot of "small streamer" setups. Currently, if you don't want to torture your camera's battery, you need to get a silly (often third-party) "dummy battery" that you can (hopefully!) plug into an ordinary USB power supply; and on top of that, a separate mini/micro HDMI -> full HDMI cable to plug into a capture card. If you could reduce that to a single USB-C with PD and DP - trust me, every silly cable you can eliminate from your setup is an enormous win.
Even better, if these cameras could talk the regular USB "webcam" protocol in addition to DP, eliminating the capture card for the overwhelmingly common setup of "I just want to look very good on video calls".
But that opens a can of worms: in any non-trivial setup, a camera (one camera) is merely a small piece of a much more elaborate puzzle. Even seemingly simple setups end up converting the signal back&forth between some crazy stuff. On one job, we needed to run an SDI or HDMI cable between the floors, but couldn't do either because the building was untouchable; so we've used a couple of HDMI -> HDBaseT converters to run the signal over existing Ethernet cables. Turns out, it was no longer possible to convert the resulting HDMI signal again to SDI (we've tried many converters, all failed), which limited our choice of video mixers. Would the signal make it through if it originated as DP? Your guess is as good as mine.
Broadcast is a strange place. I still laugh whenever I think of Quad-SDI; only the broadcast industry could ever come up with that. Things need to work with one another and even if every single person in the world agreed that HDMI must die, starting today, I'm fairly certain we'd still see new equipment being made in 2033 that supports it.