You have to look at both. Consider a simplistic example: what would prevent the new majority from holding a vote to convert the social housing into market housing? (More realistically: they owners would either lobby to change the agreement or outright break the agreement, realizing they have the community support.)

Yes, there has to be an increase in the absolute numbers. It may be acceptable to compromise on the composition of the community to get those numbers. On the other hand, ignoring the percentages altogether will produce a change in dynamics that will ultimately be detrimental to those in need of social housing.

An increase in the number of properties perhaps, but I would like to see the number of people each property can comfortably house. There's a difference between a three bedroom house and a 1 bedroom flat or bedsit.