A zoning bylaw is enforceable because it is municipal law: a building permit either complies with it or it does not, and the City of Saskatoon can refuse or revoke a permit that does not match what the bylaw allows on that lot.
There is no separate mechanism forcing a fixed number of new units into any one neighbourhood, and no penalty attached to a neighbourhood that develops slower than another; the bylaw sets what is allowed, not a quota that has to be hit.
What is worth checking before you buy or sell is what the current bylaw actually permits on your specific lot, since that shift in what is allowed can move a property's value independent of the city's $444,700 figure. Get your hand-reviewed valuation from Joel Dyck.