Although it's impossible for the burn address to ever consume the entire supply, there could come a time in xTAO's future where the burn address is very large. There is a function on the xTAO token smart contract that allows for an address to be excluded from receiving the 3% transaction fee.
Once a DAO is established, this something that could be voted on in the future if it was necessary. To be clear, if the burn address was excluded from receiving fees in the future, all the current burned xTAO will still be gone forever. Excluding the burn address will just prevent more xTAO being automatically sent to it after it is excluded.