ZB doesn't quite agree with you and made a very logical demonstration of why you are likely wrong, maybe you missed it
It seems to me that, assuming the 2wp is perfect and permanent, if everyone moves to the sidechain, the ledger remains perfectly preserved as long as the sidechain continues working. Bitcoin is no longer serving the memory function (Bitcoin the protocol/chain is dead), but the memory function is being served by another chain (and Bitcoin the ledger lives on). The store of value function has been maintained, but not by what we'd usually want to call "Bitcoin." There are some definitional ambiguities making this difficult to pin down. The word Bitcoin is used to mean:
- Bitcoin the protocol
- Bitcoin the protocol maintained by the people now known as the core devs
- Bitcoin the protocol adopted by the economic majority, or the majority of mining power
- Bitcoin the blockchain
- Bitcoin the ecosystem
- Bitcoin the ledger (who owns what percentage of the ledger)
The most notable thing about this list, I think, is that the first meanings are the most commonly used, but the last meanings are what really matter from an investor's perspective. Especially Bitcoin the ledger. A sidechain takeover threatens the protocol and the blockchain, but not necessarily the ecosystem, and not the ledger insofar as the peg is ensured and the sidechain is as sound as Bitcoin.
Now whether the sidechain will be as sound as Bitcoin is up in the air. I am skeptical for now, but again in a scenario where
everyone is moving to the sidechain that condition has presumably been met in a most credible fashion.
To me, spin-offs are a safer and more elegant way to add functionality to Bitcoin the ledger. Perhaps if Bitcoin the ledger was recognized as the real essence of Bitcoin, rather than the protocol used for updating that ledger, spin-offs would be recognized by everyone as the obvious choice. What do you think?