^ Sheppard Subway conversion to LRT is expensive ($670 million per Metrolinx estimates). Furthermore, if you want to extend that line as LRT towards Downsview, note that it cannot be all at grade. Sheppard West is too narrow between Yonge and the West Don bridge, so you will need about 1.5 km of tunneling even if it is LRT.
If you add $1.2B for the original SELRT plan, $670 million for conversion, and perhaps $600 million for the partly tunneled LRT between Yonge and Downsview, the total cost approaches $2.5B.
If we have that much extra money to spend on transit expansion, I can suggest a number of better uses for those funds (either in the Sheppard corridor or elsewhere).