Looking at some detail of the ~4.3M MPL that have not been migrated yet (query here).
There are ~8.5K small wallets with <100 MPL, holding ~152K MPL tokens, that could be particularly concerned on migration gas cost. Would aggregating them in xMPL and batch converting all of the holdings make sense?
The bulk of the MPL pending migration is in bigger wallets (and 3.6M MPL is held in 244 very big wallets). I do not see the reasons for big guys holding, unless they want to push tax gains into 2025 (conversion until April gives them enough time).
CEXs hold ~645K MPL (~341K at Coinbase, detail here).
In any case, think this proposal and MIP-012 will help unblock the current situation of split liquidity and ticker confusion.