Everyone needs to read and digest this thoroughly.
One grammar error is that I believe you meant SC proponents think BTC and Blockchain are "separable".
http://www.blockstream.com/sidechains.pdfSome SC opponents believe.
1) "To secure this value it will need to be mined,
MM is the only option as the value will be comparable to that of Bitcoin. " This is a big mistake.
Co-signed SPV proofs. Introducing signers who must sign off on valid SPV proofs, watching for false proofs. This results in a direct tradeoff between centralisation and security against a high-hashpower attack.
A futuristic idea for a low-value or experimental sidechain is to invoke a trusted authority, whose only job is to execute a trusted setup for a SNARK scheme. Then
SC blocks could be constructed which prove their changes to the unspent-output set, but do so in zero-knowledge in the actual transactions. They could even
commit to the full verification of all previous
SC blocks, allowing new users to get up to speed by verifying only the single latest
SC block.
2) They believe SC is an alt(Shit)Coin. SC is not new ShitCoin. SC is new service.
You are correct MM is not the only option. There are others.
My point remains that SC secure BTC but the value is transferred to the SC. So long as Bitcoin is more valuable one will have a motive to redeem the BTC.
So SC are a threat to Bitcoin because they separate The currency for the value in the blockchain. This will distort mining over time and predictability have a negative impact on Bitcoin.