He should be gone and already should have been, based on whatever objective metrics are on hand. At this particular time, I think fan opposition will be too much to ignore and a lack of termination will be met with some outrage.
Over six(!) years, there's always been an excuse--no RB replacement for Foster (no longer an issue), no franchise QB (no longer an issue), no WRs to complement Hopkins (no longer an issue), injuries to the offensive line (no longer an issue), and on. Like with every team, there will be issues each year, but O'Brien can't deal with them adequately. Add that to how he recklessly plays with fire in his play calling, especially on 4th down and trick plays. He's still in over his head as a pro head coach and should not have been allowed the GM reins, however much he dreams that he's Belichick. The players love O'Brien, but top talent is always set aside in the "doghouse," suggesting the same angry rigidity seen in his play calls and in the recent TMZ video, where he screamed at someone who paid the team to enter the stadium, when O'Brien is paid millions by the team to enter it.
Everyone nicknames the Texans "Patriots South," but as O'Brien's mediocrity inches closer to 10 years, the Texans are becoming more like "Dallas South" with their mediocrity matching Jason Garrett's. Unlike Jerry Jackass*, the McNairs haven't yet meddled much, but corporate malaise and inactivity doesn't win in football either. I think that dull franchise identity is reflected in the choice to make their team colors a safe red, white and blue to match any of thousands of banks across the nation.
But maybe Cal will finally remove the dullness that is Bill O'Brien.
*I've always thought of them as Jerry's "Arkansas Cowboys."