Would be nice if users could set an onchain address (above a certain amount) or Lightning address that the custodian could use in case of sunsetting the LNbits service. Users could than be asked once in a while to keep it up to date or confirm the exit transaction in their LNbits web wallet.
Users could also be reached by sending a 1 sat transaction to each LNbits wallet with a note attached including the date and additional instructions or URL where to find more information. This would allow the custodian to reach users who have connected the LNbits instance to their wallet using LndHUB.