Before I begin I want to make something clear; a recent poll shows half of Toronto opposes Ford's reductions, while a third supports it. Toronto was never going to reach 60 councillors, the public appetite was never there. Additionally, I am taking the long-term view, looking at how things will be 50 years from now, and not in 2019.
To answer why this won't last, I will simply show you two maps. These are taken from my federal election maps, but, show only Toronto.
However that's not the key problem; this is:
While Toronto's boundaries have matched riding boundaries in many elections, this is not a guarantee. Remember that Ontario's electoral boundaries match that of the Federal Government. The Feds are not going to care that Toronto wants self contained ridings.
This would either force Toronto to keep its boundaries frozen; which would mean an imbalance in the size of wards, or, draw new wards. This latter option is much more likely. This leads to the problem of "why 25 wards?" why not 26? or 36? or 66?
There are ways around this; for example, Ontario separating its boundaries from the Feds, but this would cost more money, which is something Ford is not keen to do. Ford could, however, make some sort of argument and agreement with the Feds that would see cities like Toronto and Montreal, have self-contained ridings. The simplest solution, however, for Ford, would be to add to the municipal act, that no municipality can have more than 25 councillors.
This, however, could simply be reversed by a new provincial government.