Its naive to think that the DOJ is going to make the NCAA institute a play off system. Thats absolutely not what the DOJ will do. What will happen is that they either change the way the BCS operates, or dissolves the BCS altogether. The DOJ has no say in what happens after that, unless the NCAA's solution is to institute something else illegal through anti-trust laws.
Whomever stated that will likely happen would be to go back to the old Bowl system, is probably correct.
I see it going down two ways, A) The NCAA disolves the BCS before it ever goes to court, and insitutes a play off, or B) They go to court, and the courts state the BCS is in violation of Anti-trust laws, and then they revert back to the old bowl system until something else is figured out.
But you have to remember that the BCS is in it for the money. The BCS schools are in it for the money. Going to court and basically getting told what you're doing is illegal is horrible for business. It opens them up to law suits, and the axe to their money mountain. What the BCS will most likely want to do, is somehow find a medium ground, be it a play off, or what ever, but a middle ground where they're not violating anti-trust laws, so they can still be a major part, or at least a player in the future landscaping of the football post season. They know they're in violation, they basically say 6 conferences are inherently better than the remaining conferences, with the auto bid. It creates an unfair advantage for the other conferences. The actuality of the situation is that its surprising the DOJ hasn't been involved sooner, since CFB is such a highly publicized venue.