NEW YORK ( TheStreet ) -- Brookdale Senior Living ( BKD ), the largest U.S. assisted living facility owner and operator, may have a deadline to sell or spin off its real estate to shareholders in the form of a Real Estate Investment Trust: March 2, 2016. That's the earliest activist shareholders can nominate director candidates to the board of the Brentwood, Tenn.-based company. Sounds like a long time from now, but company officials should take it seriously. According to people familiar with the situation, activist fund manager Tom Sandell will nominate a short-slate of three dissident candidates to Brookdale's board if the stock is still "languishing" and no significant moves are made before then to monetize the company's real estate portfolio. And it looks as if he has enough support to make good on the threat.