Yes, PIN is still a fallback way to log in.
As for the face, I believe the phone updates your face pretty much each time you use it, so gradual changes won’t affect anything.
Discussion
Yeah ok, but that will also be the case for forgetting most of the time. Slow deterioration. I'm talking more about the trainwreck accidents. It's good to have backups for your loved ones.
If you're super paranoid and they should only use it when you're dead or something maybe a little less bad you can still shamir's secret the digits and hand them out to friends and loved ones so they can hold each other accountable to not intentionally break in your phone.
Well, there’s a recovery contact feature for that, I believe.