Term limits would make sense, but the conservative court's Citizen's United decision would render them essentially a charade. Now that corps can basically own a seat, whoever is in the spokesperson's role for the particular corporation's seat is of little importance. They can just insert another stooge complieant to them at will, basically. The name of the person is merely a figurehead.
The exception are seats where the people actually still have much say in the vote, and any person able to buck the corporate sponsorship system are the ones we need to keep in there. Timing the independent minds out would not be to our benefit, IMHO.