The news came after the Texans completed a 4-12 campaign in Smith's 12th season as general manager.
Smith announced he is taking an extended leave of absence from his duties running the Texans to help his wife as she battles breast cancer.
Smith made the announcement Sunday after spending time away from the team.
Last week, O'Brien said he would be willing to coach the final season without signing a contract extension and said earlier this month that he "will never quit as head football coach of the Houston Texans. I remain committed to our quest to bring a championship to the city of Houston, yet my family needs me now and they are my priority".
For a couple of years now, it seems like the Houston Texans have been sitting on the fence in making the decision of whether or not to fire head coach Bill O'Brien.
Aaron Wilson of the Houston Chronicle cited many sources about the clash of egos between the two and the tension that has surrounded the squad because the two dislike each other that much.
It is unclear at this point whether O'Brien will have a greater say in personnel decisions in Smith's absence.
The McNairs want to move fast because the Texans need their new general manager and O'Brien to be on the same page because they'll have free agency (in March) and the draft (in April) to improve a team that plunged from first to worst in the AFC South this season.
The Texans were apparently deliberating whether or not to fire O'Brien at the end of this season, but that doesn't appear to be the case any longer.