I don't know about the stalking horse thing, there's room for new condos and the cc apartment market was completely ignored for a decade.
As someone from the suburbs, most of the people I knew (myself included) would have preferred much of the development to be in the city. the suburbs were nice but as every last field and farm got developed, they got less nice.
I find it hard to reconcile the statement that the main line is slipping with
just about every main line town is a transit oriented development.
"Developers are focusing on Center City and transit-oriented, high-population areas in the suburbs"
narberth, ardmore, bryn mawr...though the less storied more middle class main line tack on (west of bryn mawr) has fared better over the years (wayne, berwyn, malvern could all be considered TOD, perhaps strafford as well). Paoli remains the most interesting potential development on the line now that the Malvern project is under construction. some places have dated developments, I'm particularly thinking of St. David's and to some extent Paoli (though Pail has the old rail yards project to add new supply).
"It has shown me that everything is illuminated in the light of the past"
Jonathan Safran Foer