As of the day before the law goes into effect Apple has an app store. Apple would pretty much have to kill its entire phone business, not just its app store, which is the lions share of its income now and forever if it gave up on having any credible way for normal users to install software.
A reasonable judge would say Apple HAS an app store that it has temporarily shuttered for the purposes of a political stunt and happily fine them for believing they were immune from consequences for ignoring the law.
Meanwhile all its partners far from merely yelling at their congresscritter would be steadily losing faith in Apple.
They can't possibly be so naive.