Yes, unless their landlord is able to evict them for whatever reason. (And, to be clear, all or essentially all rental units in SF are subject to rent control).
I hadn't realized the post-1979 thing! Sorry for the misinformation above. I guess that every place I ever considered renting in SF was an older building.
1. You live in a building constructed after June of 1979.
2. You live in subsidized housing, such as HUD housing projects.
3. You live in a dormitory, monastery, nunnery, etc.
4. You live in a residential hotel and have less than 28 days of continuous tenancy.
So most of the new developments in the last 30 years aren't covered by RC.