Don't forget Blanchards! Top quality parts and top quality chaps - always served us well here and they are the other end of the country!
Biggest problem I see looming is competent workshops about who understand these older vehicles and who know how to repair them (and are prepared to repair them sympathetically). The pedant in me gets instantly het up when I get I see a client's vehicle rebuilt or repaired at eye watering expense then find rubbish parts fitted, metric fixings etc. Just had to redo all the brakes on a Series 3 88 because again poor quality shoes fitted - cooked the drums and grabbing.
Maybe a Club register of approved garages might work? there are plenty out there who like working on old vehicles and are quite capable - just need technical information and that's not always easy to find for older vehicles unless you are part of a classic car club or an enthusiast.
Philip and the team will be sorely missed in this neck of the woods, but doubtlessly we will survive. Unfortunately, most of the independents around here can make far more money out of current stuff than they can out of an oil and filter change on a Series 2. I'm working on a local solution...