Sure there was. Back in 2006ish, when they did the study of rehabbing and extending the SRT to Sheppard/Markham versus replacing it with subway. Had they started the subway then, it would have already opened.The RT was basically kaput and everyone knew this. There was no real way to save it. And Subways take a long time to build so there was no way to get it done faster.
But instead the TTC voted to upgrade the existing SRT to handle new longer trains, and extend the platforms. It wasn't the LRT to subway conversion discussion that caused the issue. It was the decision to rehash the decision to upgrade the SRT that was the problem.