I accidentally laundered mine a few weeks ago - left them out for a few hours before trying them and they were (and have continued to be) 100% fine.

Batteries are replaceable for $49: https://support.apple.com/airpods/repair/service

For what it's worth, mine survived both the washer and dryer unscathed. I just had to clean off the contacts at the base with a cotton swab.

The case is too thick to miss in a pat-down, making that scenario far less likely.