We have a tendency to overestimate the value of IAH to the overall route structure and operation at United. Both IAH and CLE have local contracts that tie the airline to the bases/hubs but when the operational cost exceed the penalties of maintaining those contracts, we'll see a pull back and closures.
Unfortunately, it could be happening sooner than later. The problems with the 737 and now the 787 are symptoms of a much larger problem at these locations.
There is a bright side - starting to see more United TV ads that appear to be going after the branding issues we've suffered since merger. Maybe OM is starting to listen to the outside forces.