If hardware wallets became unusable, would confidence in Bitcoin weaken, or would people adapt with new storage methods? Is this even a possibility ?
If this happen then provably that Bitcoin usage will get affected since we know it will be so hard for lots of people to access their funds stored in their wallets.
There are methods on how they can send their Bitcoin offline
https://www.cryptopolitan.com/how-to-send-bitcoin-without-internet/ Maybe this feature will became so popular if it happens that those situation you have mentioned would really happen.
But I believe those situations you have mentioned will never gonna happen.
Agreed.
This type of event wouldn't affect - all - the wallets probably, only some that would be targeted.