Is this the first signs of a cool-down of the San Francisco office market?

Having been through a number of economic booms and then downturns I like to be alert to early warning signs of an impending office slow-down in one of the hottest office markets in the US, San Francisco. We don’t have to worry about a suburban slow-down as Contra Costa and the Tri-Valley never took off after the Great Recession, with no new construction, almost no tech and few and far between major office leases. However, San Francisco has been on fire, with millions of feet of new Class A office space with rents $85-100/rsf per annum and a fear the City wouldn’t have enough vacant space to fill demand.  Now, with the possibility of WeWork slowing or reversing their huge space appetite, and the announcement today that Uber wants to sublease 730,000 square feet in downtown San Francisco is this even a hint that the tide may be changing? Stay tuned!