This is exactly the outcome we predicted for Alberta if our government instituted rent controls. As rent controls are instituted, investment companies sell their units and exit the rental market. There is no reason to invest in a market where costs are ever-increasing yet revenues cannot keep pace.
Supply and demand is - and always will be - the basic principle of economics. Rent control is ineffective in the long run.
Tenants love the idea of rent controls but what happens when there is nowhere left to rent?