This isn't new.  My aunt -- who lived in Marin County at the time -- said that she and her husband actually looked into buying a "shared ownership" property 30 years ago.  She said that kind of arrangement was available in places like La Quinta, Tahoe, Napa, Carmel, et al.   And no, it wasn't a timeshare.  It was shared ownership.  Not sure why this is suddenly news unless it's because the neighbors are in an uproar.  Not that I blame them...I was a NIMBY myself at one time so I see both sides.  But the writers of the article make it seem like it's a new deal.  It's not.