The original 2014 study had 4 lanes across the entire corridor minus Avenue-Mount Pleasant.
This is what Metrolinx partially built-out as a part of the Crosstown - the major intersections near stations were done accommodating 4 lanes and bike lanes, and in many cases a turn lane too.
It may cost the city more to keep 4 lanes as they may have to move curbs in some places, which costs $$$, but it's definitely possible. They had a whole preliminary design from a decade ago with it done that way.
The reality is that the City should have found the money in the first place to do a proper rebuild of Eglinton to the full Eglinton connects vision approved in 2014, which includes dedicated cycle tracks, 4 lanes of traffic, upgraded streetscaping, etc.