Werbil
I feel you are close, in that you intuitively go beyond the today paperwork to the likely end state.
ADS-B IN and TCAS. Computer based systems. Input data altered by software to provide information. The capability exists - it is usually the TSO and the need for extensive testing (and rightfully so where safety is concerned) that delays the final equipment. And, even then, the equipment will be in accelerated change state due to technology push.
ICAO Annex 6 - the part we need to consider - relates to airspace and access. The 2003 revision is worthy of our consideration for what it MIGHT likely do to GA and airspace sharing - if we don't do it better first.
Think through the note to 6.13.2 (Recommendations):
The intent is also for aircraft not equipped with pressure-altitude reporting transponders to be operated so as not to share airspace used by aircraft equipped with airborne collision avoidance systems.
Might be better to work out a technological way to share than find ourselves with exclusionary airspace. Initially, only demands Mode C transponders. What is likely when the world moves into ADS-B mode?
The Australian opportunity for FREE ADS-B fitment shifts later this year to 2028. If it is not pursued, one suggests ADS-B will be ICAO mandated a long time before 2028 - at OUR cost.
So, returning to your question, Annex 6 itself does not suggest your concept - but the logical flow on of ADS-B adoption and the EXTRA information provided to TCAS by ADS-B data - suggests the very end state you describe. But, the long road does not begin until the first step forward is taken.