As someone who's spent a lot of time in this space and is quite interested in lowering the cost of entry and finding ways to simplify it, I'm afraid you've vastly oversimplified the problem.

> sports fans certainly don't care about recompression quality loss...

I think that's quite an assumption. In a modern video chain youd need to decompress and recompress the video from a camera many many times on the way to distribution. Every filter or combining element would need to have onboard decoding and encoding which would introduce significant latency, would be very difficult to maintain quality, and would introduce even more energy requirements than the systems we already deploy.

High quality cameras aren't any good if they throw away their quality at the source before they have an opportunity to be mixed in with the rest of the contribution elements. You certainly wouldn't compress the camera feeds down to what you'd expect to see on a consumer video feed (about 20Mbps for 4K on HEVC).

> normal networked transport like H.265 with MPEG-TS over RTP

If you want to, you can do that already using SMPTE ST 2110-22 which loops in the RTP payload standards defined by the IETF. ST 2110 itself is already using RTP as its core protocol by the way (for everything).

> do time sync by having A/V sync

What do you mean by this? In order to synchronize multiple elements you need a common source of time. Having "good clocks" on each device is not enough: they need to be synchronized to the level that audio matches up correctly, which is much more precise than video as audio uses sample frequencies in the 48Khz-96Khz range, whereas video of course is typically just 60Hz. Each clock needs a way to _become_ good by aligning themselves to some global standard. If you don't have a master clock like PTP, your options are... what... GPS? I mean you _could_ equip each device with its own GPS transponders, but if the cameras cant get a reliable GPS lock then you're out of luck.

> aligning based on audio loud enough to be recorded by all devices

Do you mean physically? Like actual audio being emitted into the space where the devices are? Because some of the devices will be in the stadium where theres very very loud noises on account of the crowd, and some of them will be in the backroom where that audio is not audible. Then you need to factor in the speed of sound, which is absolutely significant in a stadium or other large venue. None of this is particularly practical.

If you mean an audio sound that is sent to each device over a cable, well are we talking SDI (copper)? If so, we wouldnt use audio for that, we would use what's called Black Burst. But what generates the black burst? Typically, its the grandmaster clock. The black bursts on SDI need to be very precise, and that requires a dedicated piece of real time hardware.

If you mean sending it over ethernet, you now need to ensure you factor in the routing delays that will inevitably happen over an open unplanned network. To deal with those delays, we typically do two things. One, we use automatically planned networks, where the routers are aware of the media flows going over each link, and the topology is automatically rearranged in order to minimize or eliminate router buffering (aka software defined networks, typically using NMOS IS standards to handle discovering and accounting for the media essences).

Exploring a Modern SMTPE 2110 Broadcast Truck