I have few USB flash drives which have 'died'. Is there any estimation how long those current hardware wallets on the market, for example trezor or ledger nano, will last?
Well that is basically a fact we all cannot avoid. Nothing lasts forever, so we really have to keep our secret keys secure somewhere so we do not lose our bitcoins or at least keep the seeds with you so you can restore all your coins when your hardware wallet dies.
By the way, maybe the better wording for your tittle should be "hardware wallet" and not physical bitcoin wallets.