Masks aren't going anywhere, at least for the time being. It seems like Apple has accepted this, as the latest beta software on iPhone lets you use Face ID with a mask on without using an Apple Watch. However, you'll need to have a newer iPhone to take advantage of the change.
We first learned about the change to Face ID yesterday, but Cult of Mac did a little extra investigating and found that you can only take advantage of unlocking your iPhone while wearing a mask if you have an iPhone 12 or 13. Older models will unlock as they always have, even after updating to iOS 15.4.
Additionally, after further testing, it was discovered that you could use Face ID with a mask with Apple Pay, which is a significant upgrade over the way Face ID and Apple Watch work on current iOS versions. You can also use it to unlock protected apps.
Currently, iOS 15.4 is in beta, so you'll need to enroll in Apple's beta program if you want to start unlocking your phone with a mask on. Otherwise, you'll have to wait until the new iOS version rolls out to the general public, which should be early in Spring 2022.