They're just a short-term fix.
You've got it backwards. Layer 2 solutions are long-term. Short-term would be arbitrarily tinkering with the block size, just as many altcoins have done over the years. And that's true, because it's infeasible to have every person on-chain, creating multiple transactions every day, at the scale of hundreds of millions of people, while simultaneously being practically able to verify the ledger.
bitcoin will never be the "one world currency" (dystopian myth) you portray bitcoin needs to become in your dumb scenario about scaling
bitcoin does not NEED a fee war to support miners to produce a difficult hash for blockchain security right now. so dont drum roll that myth either pretending fee's need to rise right now
the actual long term solution is not eventually high fee per tx.. nor does it require a massive single jump to "hundreds of millions of transactions".. nor does it require migrating everyone away from bitcoin to some middleman managed subnetwork
however a SCALING (periodic growth) of transaction count increase will be needed whereby the more transactions occurring onchain means each individual is nor forced to pay absurd amounts
subnetworks have a place for small niche sub services of certain facilities and functions but subnetworks should not be the primer network everyone is forced to use.
bitcoin does need to scale as long term solution. and befor you cry about your myths, its called scaling not leaping. so dont reply with your rhetoric about leaping to huge blocks or needing huge fee's with restricted tx counts(purely to support migrating to other networks)
P.S
i do laugh when its blackhatcoiner mindset that thinks 1 bitcoin transaction could and should increase to $50+(emphasis ONE TX) but then cries that a $50 hard drive that can store decades of transactions(hundreds of millions) is something too expensive