I'd argue that it shouldn't be grade-separated.
Now hear me out. I would've liked for it to have been grade-separated, so long as the Laird to Kennedy section was grade-separated too. This would've been a decision in the previous decade, or during the MOU. With that we'd no longer be building an LRT line. It'd be a subway, and we could do away with the whole overweight low-floor LRV situation. It'd be sleek 75-100m trains. Scarb Ctr to Pearson all automated. Now deciding to have the Mt Dennis to Pearson section grade-separated, and particularly tunneling under much of an expressway corridor, doesn't add up when we'll have trains along Leslie to Kennedy stopping at every intersection. We're past the point of not having the Crosstown be an LRT line, so let's just continue with what was planned. Largely tram-style to Renforth or Pearson will still be super awesome.
As for the portion east of Kennedy being realized, that's a bet I wouldn't put money on personally. Not to say it doesn't have enormous merit and shouldn't be built. But I think it'll be way costlier, complex, and contentious than many realize. And that's even when mentally excluding the section past UTSC and turning toward Malvern, which I def don't see happening.