So, I see 2 things that are positive and interesting in recent announcements.
1. The use of aircraft to aircraft passing of information rather than relying on ground infrastructure means that there should be less of a single point of failure to the system. However, as @MattL says, it will be interesting to see how the correlation of aircraft track information from different sources doesn’t generate multiple tracks on a display (or stop displaying the best information information). That was a problem that early JTIDS L16 had to overcome. Sometimes a 4-ship became a 16-24 ship! Achievement of that is really impressive using Raspberry Pi processing.
2. The recent EASA announcement of a common signal format to be used by ~50,000 in use 860 SRD frequency using devices means that there could be just 2 common frequency standards for direct signal detection of each other - this new common 860 SRD EU standard and 1090Mhz ADS-B. So with just 2 signal formats then there could be systems that should be able cooperatively see each other. The only other idea is the 978Mhz “ADS-B Lite” signal standard and also a rebroadcast function. So the race is on really - will 978 or 860 SRD win through. Or will it become a 3 horse race to allow a non-aviation use frequency to be used. I personally believe that the idea of using 4G/5G mobile will fall over.
So my own vision is this - for it to work it needs both systems to do exactly what is required:
1. A 1090/978 MHz ADS-B system that can tx/rx between each other with an ability to see others on the 860SRD either directly or via rebroadcast (like that seen at Goodwood/Lasham and other trials).
2. An 860 SRD common standard that can tx/RX between each other with an ability to see others on 1090/978 MHz ADS-B either directly or via rebroadcast (like ATOM and SkyGRID).
If that comes off, then that would be excellent