It seems likely that the owners will "change their mind" and decide to convert the "storage area" back into an apartment once the tenant is gone and they can rent at market rate again.
Remember, according to the link, the landlord has gone through some efforts to make this hard to challenge, including legally changing the status of the building to single-family. That's a very difficult process[1], but the reverse is even harder. (If converting single family dwellings into multi-tenant units was easy, San Francisco wouldn't have much of a housing crisis.)
Given the huge legal obstacles, plus the fact they already removed the bathroom and kitchen (not cheap), plus given the already strong trend of multi-unit dwellings being converted into single-unit dwellings to fuel demand from the rich, it seems unlikely that this building is going to be multi-tenant any time in the foreseeable future.
(Unless the landlord screwed up and didn't get the paperwork done. In which case they won't be able to raise the rent. But that doesn't seem to be the case.)
