In San Francisco the pendulum has definitely swung back closer to center (the scale being all open to combination of open and private to private office intensive) with most startups occupying a hybrid solution with a myriad of breakout rooms and smaller meeting spaces / soft seating.

The trend over the last decade began with die-hard open office plan fanpeople (breaking free of dads private office intensive historical), who quickly found that there was a lot of counterproductive distractions. From there as more traditional business starting adopting a start-up mentality to their office space, a balance had to be struck to ensure productivity.

Now the offices of Airbnb, Optimizely, Weebly, all have very strong distribution of open communal work area with solid guidelines from a cultural perspective on how to treat people in that environment, while also matching the open area with ample meeting space distributed evenly throughout their building.

With a more thoughtful approach than just open vs not open I think a balance can be readily created while also speaking to the culture of the company and genre of business it functions in (gaming, Saas, mobile, etc.).

For the record 1- 10 years 2- open (3.5 yrs) vs closed (6.5 yrs) 3- dozens but you learn the headphone rule which basically means (don't bother me or text / message me)