The idea of (almost) everyone participating in the ADSB game is a noble one.
But its still just too expensive.
Asking VFR aircraft owners and operators to shell out $5k for a slight (possibly?) increase in safety benefit is just further impost to a declining and already financially overwhelmed General, Recreational and Sports Aviation industries.
If the cost (fully installed including all taxes) to play one day falls to less than $1k then perhaps it might catch on without mandate.
Until then I'll keep using the transponder, radio and Mk 1 eyeball.
PG