You take a pension fund like Quebecor which has been a major player buying up newly built rental buildings all over Canada leaving the developer a minority stake and management rights. If they stop buying based on stagnating values than that will affect developers raising capital to build rental towers. Rental is a terrible investment based on income. The attraction since it started has been booming real estate values. The Canadian Pension Plan is another that has turned a deficit into a surplus investing in rising real estate values of the last decade