I would guess that for the time being, the large employers who are subject to the mandate aren't going to roll back their plans to make employees comply, probably for a couple of reasons.
First, it probably makes good business sense from the standpoint of trying to get their employees all vaccinated. Second, at any point in time there could be another court ruling that the mandate is back in place, and it's not like companies can just snap their fingers and get these things implemented.
If I were a large employer, I'd just continue with the roll out. If it turns out that the mandate is ultimately ruled illegal, no harm. The companies will then know that they don't face any fines or penalties for any errors or lack of enforcement that they might make.