Another interesting possibility is Kennedy LRT. That will be feasible if the Danforth subway extension is selected, and takes the McCowan route rather than the existing SRT path.
Then, the former SRT guideway from Kennedy to Ellesmere can be used for the new Kennedy LRT. At Ellesmere or at Progress, the LRT will tilt west and switch to Kennedy proper, continuing up to Steeles and possibly going into Markham at a later date.
Advantages:
1) Rail service to the Lawrence East cluster is retained.
2) The line will serve Kennedy Commons, Agincourt Mall, and Pacific Mall at Steeles. Hopefully, that will ensure robust ridership counts.
3) It should not be very costly to build. Almost all new tracks will be in street median, and no need to cross the Uxbridge mainline.
4) Such a line will create a network connection between the E-W light rail lines: Eglinton, Sheppard East, and potentially Finch East.