To maintain the anonymity goal you still want to obtain Talers in advance (otherwise you'd open yourself up to timing correlation) - so they will have to be in the wallet for some non-negligible duration.

Regardless of expiration that also means the device holding the secrets to use the Talers can be lost in that time, so you need some e.g. encrypted cloud backup to restore from. Since people are terrible at printing out recovery codes, you can either have key escrow (leading to a compromise of the anonymity properties), or you accept that some people will lose their money for reasons they will not understand.

Regardless, I would much prefer Taler as a CBDC to whatever permissioned Blockchain garbage the Big4 consulting companies will come up with.