When the Department of Justice went against IBM during the Nixon administration, IBM looked invincible. The Reagan Justice Department dropped the suit, but IBM doesn't seem so formidable today. The same thing would have happened naturally to Microsoft without the antitrust suit, although it might have taken another 25 years. The antitrust findings just sped things up. The risk is that speeding by tinkering may cause an unnatural result that unreasonably impairs or even destroys one of the most effective and productive international competitors this country has ever seen.
All monopolies are inherently inefficient.
When you own the market, muscle atrophy creates fat, complacency and the distorted notion that you really deserve to own the market. This is the very atrophy that eventually would have ended Microsoft's dominance, even without government intervention. But only the market should decide. It might take longer, but the result is more natural. This is not an industry subject to X-ray diagnosis.