That's a great point about how obvioue collusion would be. Again, I think miners stealing is good.

I don't agree at all with your second point though. Why would the balance in the 2wp ever be very high? You could instantly swap in, do your zero knowledge coin mixing or prediction market bet, then instantly swap out. Plus, if you think that a drivechain can capture even 10% of the market for monero or zcash transacrion fees (not to mention ethereum) then mm revenue could be pretty nicr for miners.