This gets into enforcement of any rule for that matter at, for example, WDW. Front line castmembers are not empowered to do anything other than politely asking the guest to comply. I have seen stories of security simply trying to get folks to leave the Hoop de do Review after the last show spin out of control quickly.
As usual, there will be guests that comply with rules and there will be guests that do not, no matter the rule.
In my opinion, Disney will not suddenly become hard core and have a gray shirt squad to eject guests that do not wear a mask. This is going to be interesting to watch.