The obvious solution is to let Bitcoin be the lightweight timechain it's meant to be and install a proof scheme for another data storage mechanism.
Keep the supply cap, make sure coins aren't double-spent, publish proofs globally, and that's it.
Then, make L2's and L3's to accelerate and expand. Use larger and more frequent blocks on a side chain that get's purged to 1-year, and publish the top-level proof on Bitcoin, including swaps with Bitcoin and sibling chains. Make lightning channels on the side chains, bridge them, etc. Bitcoin get's to stay lightweight and secure while getting scaled.