I've heard that LRT isn't out the window just yet too. Honestly, I can come around to the idea so long as it is a continuous line from Sheppard West to Sheppard East/McCowan. No Linear transfers and it can be what Eglinton is supposed to be in a more appropriate context. While I think we'd have growing pains with this if we do make it LRT, at least it's possible in a reasonable timeframe.
Worth noting the Ford Government's aversion to new LRTs, and also that they are willing to throw around the phrase quite loosely. Recall the "interregional LRT" in the MTO's GGH 2051 Plan is almost certainly going to be Ontario Line style Light Metro. The point being, LRT's definition is sometimes broadened to everything short of a TTC Rocket. I would cautiously assume they do mean at-grade LRT right now for fear of being let down, but a ploy to weave (and perhaps interline) Line 4 into the Ontario Line would certainly not be unwelcome.