L2s have their own major trade offs. Will never be a complete substitute for Monero. Lets see we have Ecash(custodial, rehypothecateable) and Liquid(permissioned, only hides amounts) so far with all their other problems. Unless you like your privacy with a side of cuck, Monero will always be used. Monero is also not static and waiting for yall to catch up. It is constantly improving it's privacy.
Any minute now Bitcoin will have it's major privacy solution. Just wait a few more years bro it will be on Layer 4. ⏰