Well, the way i see it.
If say a rent costs 0.00005 BTC, then the rent they pay will be 0.00005 BTC even if the market fluctuates. so they cans till pay rent technically.
Stop thinking that the USD gives value to everything in the world please. Currency of other countries fluctuate as well with value over USD but rent does not change every month does it? Please stop with USD supremacy. US is not WORLD.