While there is a possibility that the ROW will be used for the Sheppard Subway, I highly doubt the existing guideway would be able to support it. It would most certainly have to have the guideway removed and rebuilt to something that would support TRs, as well as with 150m long stations in mind. Failing that though, it would be cool to see the ROW used for some sort of future York Mills LRT (to eventually replace the DSBRT), but I have no faith in the city's ability to maintain the ROW and not build over it.