All coins are stored on the blockchain, now hodl on to your hat - there are no coins in fact, Blockchain in general works as a giant record book - a ledger of transactions - and your private keys allow you to sign transactions from one address to another and hence changing the balances. The fact that only the owner of private key can signs a transaction from certain public address in combination with the need of having the transaction confirmed by the network ensures the whole system is secure and working.
As all addresses in Trezor are derived from the seed it means that all of them can are connected to this seed forever. Also, seed can generate pretty much every address by using certain mechanism.
More information: Learn about: Recovery seed