BM,
fishing?
ADS-B will be more than a a replacement for MSSR radars; it will more than likely prove to be more accurate than MSSR radar, has so far also gives better range; it updates more often and it is auto slant range corrected as it's using GPS data (digital data stream" sent to it, i.e. not a "reflection". Problems occur when airborne equipment fails or in times of GPS tollerance failure; but not very different from tansponder failure in the MSSR climate.
The issue will be fleet (GA) compliance; will the fleet have to buy a squiter or will it be supplied? If supplied where does the money come from, given that there is currently a team examining the ministerial direction compliance and accurately costing the 10 new radar heads...
ADS-B roll out may be too late to save the money, the"bucket" may be so empty that industry will have to 'hand in own pocket' to by a squiter; which means it won't be coming in anytime soon. Because I would imagine that would be resisted. Also the initial plan is for high-level ADS-B coverage FL300+; which of course will provide many areas of low level coverage; better than exists today, it probably won't enable a hand-out to all as the target audience is FL300+. If the FL300+ 'trial' works really well then the other sites (and squiters) will be progressively rolled out, I would guess. At about $200K per ground unit; you get the 30 sites for the cost of one MSSR radar, with almost no maintainence costs; no moving parts...