Forcing GA with compulsory TCAS sort of gadgets will not solve the problem - It will just pander to the 'gadget brigade' who never look out enough, and won't show up the non squawking traffic.
A gadget is a self opening bin or a touch sensitive light. TCAS is the ABS on your car or the system that stops trains passing red signals (TPWS if you're interested
).
When our phones have the power of supercomputers there is no technical reason why EVERY aircraft, including UAVs, can't broadcast its position.
That only leaves geese, but even A320s have problems with them.