For one, the Eglinton east part is already under construction so this is just a rehash of the Scarborough subway/LRT debate.
1. The provincial government will go with whatever the city wants. They waffled before and they'll waffle again. See what
KW's response was when asked if they'd go back on the subway.
2. City Council voted 24-20 for the subway. The three principle backers of that (Stintz, DoFo, RoFo) will not be on council this time next year. This all depends on council's composiiton in 2015, which I sincerely doubt will be as Scarborough subway friendly.
3.
Here is Metrolinx saying that light rail was the best solution.
Here is the TTC's report, where they state a preference for it, and that they
are still working on it. Where are you getting that they're opposed?
4. RoFo is probably off the table. Tory said the scarborough subway was "barely justifiable". I'll admit that it comes down to whether Tory or Chow wins the mayoralty.
The "third option" of Scarborough LRT is still technically on the books as the
official plan, as per the master agreement.