Therefore, it seems to me that the argument against sidechains should focus on why these assumptions are not likely to be met (mining issues), which is a situation that will mess with the ledger (though only if people get duped into putting too much money into SCs).
that's what i am trying to do.
i would also submit that a ledger that carries speculative assets (anything other than BTC) will be different ledgers as they will be less secure as they aren't likely to be MM and will be priced in the market differently.