[digianarchist]

Is anyone confident that Apple will win on appeal?

By the effort developers putting into payment-flows I would say they aren't, but depending on the volume it could be purely for short-term gain.

[threeseed]

Courts don't care about the amount of effort developers are spending to take advantage of the window before an appeal has been ruled on.

[techjamie]

I think the implication that is being made here is that the other companies have examined their odds, and determined that the odds are good enough that they would dedicate the resources.

Which, presumably, means their legal teams examine the case and think that the appeal won't succeed.

Though there is always the possibility that it was relatively inexpensive to implement, and the increased sales in the meanwhile during the legal battle will outweigh the cost of changing it.