The time is now, I encourage all to remind city council that this is their moments to redefine Toronto by doing this right.
I agree that now is an important time to invest in the best transit projects, and to make bold investments worthy of the great city we are. I'd advocate committing to building the eastern part of the relief line to Lawrence now (not stopping at Danforth). Someone should emphasize to Trudeau, Wynn, and Tory the opportunity to solve major transportation and environmental issues, and also leave a legacy by reconnecting the city with the Don River in creating an unprecedented park that connects many Torontonians.
In the thread "re-routing rail away from the Don..", I discuss how rail can potentially be removed from the flood prone Don river, enhancing public access, while the rail traffic can be re-directed in an interlined relief subway line. Others have suggested this scheme, and I did some rough visuals posted below based on my interpretation. A commitment to build to Don Mills and Lawrence with appropriate tunnel infrastructure and junctions would allow for the Don River Valley "superpark" to take shape. To get it done, it would take high-level leadership and coordination among these politicians, and probably not that much more money than is already on the table. There are few opportunities for politicians to enhance their capital on multiple fronts with one bold project, but this may be one in my opinion.
About the DRL/GO interline scheme depicted below -- GO Richmond Hill would still depart from Union, but would begin to interline with the DRL around Gerrard Square (a junction would be built into the station). The interlining would continue via tunnel (three tracks) all the way up to Don Mills, just north of Lawrence, where the GO train would emerge from the tunnel onto the existing tracks to Richmond Hill. The RL could also continue north on the above-ground rail up to Sheppard (if DRL uses RER rolling stock, not TTC subway trains, as gweed123 suggests below). The suggested routing would make it unnecessary to re-activate the Leaside Spur. The train tunnel would cross the Don Valley via a new bridge built alongside the Millwood Rd bridge. The station at Eglinton/Don Mills would include direct transfer to the Eglinton Crosstown line.
Anyway, these are just intended to be discussion starters, and I know there are other good alternatives.