The coins still need to get onto L2 in the first place.  That's a transaction, so if it's dust, it's not getting on.  

But as a general strategy, getting your stash onto some L2 somehow is the way.

I think the unkle jims LSP and Ark and cashu and fedi and liquids are being a little underestimated here. Even if mainchain fees stay really high, there will be some half self custody local situation that everyone can have... Also side note can liquid or a similar side chain suck up the dust UTXOs?