Mixing a C150 and an F16 in the same bit of airpace with a Controller only talking to one aircraft is bad news from the start.
I do not think technology alone will not provide the solution to this problem, same for UAVs integration in controlled airspace btw.
Unfortunately segregation is the only safe way for the moment.
The current "GA" ADS-B does not work well for anticollison , especially in the arrival/departure phases . I know , I use it on my small GA aircraft, it is verty nice to have, provide an extra layer of alert, but in a busy environment, for a single pilot flying by hand at low speed , forget it, it can even be counter productive .
For a one to one encounter in the pampa, yes, but say, taking the Easterly VFR inbound route to Vegas North around an active Nellis AFB ? forget it.
Watch and scan outside all the time, ( no head down watching a display) and talking to ATC still are your best anti collision and will remain so for a long time .
I also feel sorry for everyone in this collision , because a simple procedure , like e.g. VFR deps stay below 1500 and IFR stays above 2000 until re-entering class C or redesigning the class C to protect the ILS would not involve high tech, cost near to nothing to implement and would solve the problem.