I don't think this strategy would work. Even if young people decide to forgo buying housing, they still need a place to live. Ergo, they will rent. Which will mean demand will still be the same. 

Housing is expensive partly because demand is always constant. No one can just abstain from the market.

yes but

(i) rent demand != buying demand; the former sets a floor on the latter but the latter can fly high on its own
(ii) you can abstain from the market on the margin by living in smaller or less-prime-location homes, not buying second homes... this can make a big impact

Not only can you abstain by living on less desirable land, you can also coordinate with your community members to tithe a standard portion of your income, which reduces everyone's ability to bid up the value of land. Widespread tithing is a crude approximation of a voluntary land value tax, with room for improvement!

(ii) that’s called being priced out in the U.K. Prime locations are usually owned by the grand generation.

agreed. down-scaling en masse can be an effective lever to force prices down, wether you own or rent.