I suspect the funding answer for Rail Deck Park, and possibly even the implementation, will come from the federal level. There's still the matter unresolved of ownership of the land...*jurisdiction of the land* let alone the air-rights above it. Last legal reference re: The Esplanade Corridor (USRC) I can find is:
[...]
The Dominion statute could not give capacity to the City of Toronto. This was done by the Ontario statute. The Dominion statute was necessary to make the scheme agreed topermanent and final until otherwise provided for by Parliament.
Section 1 enacts that all works done or to be done in order to give effect to the agreement hereinafter mentioned, as well as those affected by it, are hereby declared to be works for the general advantage of Canada.
They cannot, therefore, be considered as private works of railway companies. They are to all intents and purposes federal works remaining under the exclusive jurisdiction of the Dominion Parliament, under section 92, par. 10, of the British North America Act.
[...]
https://scc-csc.lexum.com/scc-csc/scc-csc/en/9855/1/document.do
Ostensibly I'll have more to add to that later, it is being studied by a number of Toronto MPs.
A search is being done to find any amendments or later acts that render that finding inapplicable. So far, none are showing, and it's still the purview of Parliament.
ADRM is right, and we all know this...Toronto's coffers are not only almost dry, what's left is committed many times over to a list of other priorities. Yet again, and not entirely by poor civic governance alone, Toronto wears short pants. His Almighty Worship certainly doesn't help with his histrionics.