CKLW FM would have moved to some sort of a rock format back in the early 80's, but I am not sure it would have been the same format as CKLW AM. The Big 8 had a dated sound by the early 80's and was already moving away from top 40 and more adult hits. CKLW FM could very well have ended up with a album rock format which was popular at the time in Detroit. If CKLW FM had adopted a top 40 Big 8 format, what becomes of CKLW AM?
In the early 80's in Toronto, CHFI, Q107 or CKFM would have been more likely to flip to top 40 if it had been allowed on FM. But what happens to CFTR which was doing well on AM with top 40 if CHFI flipped? Simulcast CHFI and CFTR? Not going to happen. CKO was struggling with it's all news format and making no headway against news heavy CFRB, CBC and CKEY AM. So all news wouldn't be an option for CFTR.
CHUM AM and CKOC would have had to find an FM frequency to move to. CKOC didn't have an FM sister station until 1986. CHUM FM was doing well in the early 80's with it's album rock format, so not so sure they would have flipped to top 40. In the early 80's oddly enough CHUM AM was sounding less and less like a true top 40 station with a heavier format that included album cuts.