I agree it is unlikely to happen—and I agree that Congress goes for even the small-bore financial gains for itself when it sees the opportunity.
It would also cause a firestorm with workers that get the break. In the past, my employer periodically relayed how much my coverage was worth. They just make an educated guess because they are self insured. It was a group price figure and not based on age. I think it was the Cobra cost. If they would have taxed me on that it would have the royal shaft in my younger days. For a family of 4 in the 25% tax bracket, it would be a ~$7.5K tax increase today.