What happens if Trezor and Ledger shut down?

What happens if hardware wallet companies shut down and you still have your private keys? Trezor and Ledger both use 24 letter mneomic phrase keys but traditional software wallets gives only a 12 word one.

So in the case that you lose your hardware wallets and need to restore them – where can you do that if no wallets seem to be compatible with the 24 word format?