As always people see the happy path down the middle of the forest, not the creatures waiting to leap out and eat them two steps down the line.
"Is your stuff going to keep working? There's literally a website dedicated to the products Google has killed. What makes you think you're so special that they won't do that to something you use?"
Of course, you're probably sleeping on the couch that evening...
GF: "If my stuff keeps working, why is it a problem?"
BF: "Is your stuff going to keep working? There's literally a website dedicated to the products Google has killed. What makes you think you're so special that they won't do that to something you use?"
GF: "If Google deploys this and then kills it, my stuff will keep working. So why is it a problem?"
...and she would be right. If it doesn't break her stuff when some websites start relying on it for user device attestation, then if Google kills it making it so sites can no longer use it for user device attestation those sites aren't going to just say "Oh no! User device attestation no longer works! Let's shut down the site!". They will go back to whatever they were doing before it became available.