My reasons for opposing Drivechain:
1. Today, miners are purely profit driven. Work in -> Bitcoin out. Drivechain introduces political incentives: which chains to activate/deactivate and when.
2. Since miners vote on sidechain activation/deactivation, a 51% miner can unilaterally decide each side-chainās fate. Including the ability to take all sidechain coins for themselves. This is a new incentive for 51% attacks that did not previously exist.
3. Pegs are made to be broken. The time lag for peg in/out guarantees arbitrage. The second-order incentives around sidechain rollbacks are unpredictable.
4. Drivechain will not kill shitcoins. The main point of shitcoins is pump-and-dump. If the pegs are successful, shitcoiners are disincentivized from choose them over spinning up their own chains.
5. Contrary to supportersā claims, Drivechain cannot increase miner revenue. The subsidy schedule of Bitcoin is immutable. So the only way miner revenue increases is by fee pressure. But a supposed benefit of Drivechain is to move transactions off of main-chain, which would reduce fee pressure.
6. Drivechain requires softforks to implement, because new OP codes must be enforced by nodes. But regular main-chain users have no incentive to adopt these rules. This makes the risk of total reversal greater than previous softforks that directly benefitted regular users.
7. Drivechain proponents systematically ignore these concerns. A common refrain is that activating Drivechain will not affect users of main-chain. But the risks of arbitrage schenanigans, miner politicization/centralization and softfork rollback deserve clear answers.