I don't know if it is a new problem or not, but the explanations and creation of understandings in the minds of the broader public may be made more difficult by the "one ledger only" notions. EmptyGox very clearly had its own ledger which at some point became irreconcilable with the Bitcoin block chain. If it were a side chain company that had monkeyed with its code to do these shenanigans, it would possibly been more noticeable (if it were being openly mined by folks that examine source changes), but if they managed to keep it hidden, or were privately mining (like Ripple?) it may also be more difficult to explain to the "one ledger only" believers how this is possible.
In the earlier example where scBTC1 failed and scBTC2 became an altcoin, at some point in this process there are very clearly (at least) two separate ledgers.
I would suggest that at the inception of each of the side chain's block chain, there and then emerges a new ledger, which are each potentially merge-able. Others might suggest some other time. Maybe at one of the many changes that resulted in the failure of scBTC1, or maybe after it fails, or maybe never and the scBTC2 altcoin and Bitcoin are still just one ledger. In that case, when the ledger of scBTC1 failed, some might get confused and say the Bitcoin ledger failed. (Since they have been told that there is only one ledger, and something failed, so it must be that.)
It seems simpler and more sensible to me to consider each side chain its own potentially merge-able ledger. It is hard enough to try to explain how a ledger is merged with "something" when there is only one ledger in the first place, with what then is it merged?
I think the notion that there is one main ledger is absolutely accurate
In my view, the more accurate definition of sidechains are that they are a sub-ledgers of Bitcoin.
I would suggest that at the inception of each of the side chain's block chain, there and then emerges a new ledger, which are each potentially merge-able.
This is the part where I disagree. There are no coins in a sidechain at its inception therefore there is no ledger. The ledger is only created once coins derived from the main ledger (Bitcoin) are locked into the sidechain.
For that reason I believe the best way to describe it is one main ledger equipped with several other sub-ledgers that derive their monetary unit from the main ledger.
Lol, earlier on you admitted to me we were dealing with "different" ledgers after I had to correct you .
Answer this, what ledger with integrity allows part of itself to be cut off from its main body as in NL's SC2 scenario?