Speaking to those developing UHD broadcast technology - the move to 100/120fps is definitely on the radar in the future. 2160p50/60 simply has too much motion blur for high speed content like sport.
NHK - who developed (or are largely the driving forces) behind our current 1080i HD and 2160p UHD systems are pushing very hard for 4320p120 (i.e. 8k120) with a 2160p120 and 2160p60 downconversion for 8K and 4K sports. They are running a 4K and 8K channel in Japan - and I believe this has included some 120fps trials.
The BBC has worked with the EBU to trial 100fps stuff over the last 6 years or so. It’s not here yet - but it’s definitely on the horizon as a possibility - particularly now we finally have a >60fps timecode standard (which was a real problem and forced dual-phase p50 or p60 to be used)
The move to IP control rooms - rather than SDI-based production facilities - is also a major route to adoption.
Sky may only run a UHD overlay DVB-S2 system - but BT Sport’s multicast IPTV system carries UHD services, the BBC iPlayer does, and the major OTT players for Sport are beginning to as well. Tokyo 2020 would almost certainly have seen a bit of an explosion in UHD sport (as Japan was planning to host at least some of it in 4320p - and some of that was due to be p120 I believe)