I wouldn't be all that hasty... D-Rob was definitely not playing like a franchise corner, but he was above average. And I wouldn't rank either Quin or Reeves as being better.
I'd love for the league to fix the transition tag. Make it top 15 or 20 salaries, as opposed to top 10 and let an arbitrator pull any poison pill provisions.
Have a look at the FA CBs you'd look to replace him with:
http://www.footballsfuture.com/2010/fa/db.html
Richard Marshall is a RFA, and I don't see any one else that I consider an upgrade. The last thing I want to do this off-season is open up any additional holes. The draft is pretty shy on start from day 1 CBs as well, and most will go before we pick.
My plan for the Texans' is to keep reasonable talent at all positions. Get the FAs that provide the best value, and draft the BPA's. Hopefully we can get away from 1st rounders have to start in year 1, and get to an all draft picks will have to win the job. That's how to get a long-term successful team.