I think this is right. The same using other words: There is a separate value for the scBTC. When the peg is broken, this value is revealed. It also means that while the peg is intact, the holding preference would be with bitcoin in cases #1 and #2, and with scBTC in case #3. This will suppress the usage of scBTC #1 and #2, and may render them less and less liquid.
The problem for scBTC in case #3, is that it first will have to survive a period with less freefloating value, so it will have a problem achiveing the status of #3.
Blockstream are attracting big clients, they want to run entire countries on SideChains, one way to grow it is to do a 1934 Gold Reserve Act and have everyone convert, they could even do it at favorable rates above current exchange rates. you cant dismiss #3 is the point I'm making.
We have been repeating this ad nauseam but countries willing to run their fiat economy in crypto will preferably issue their own altcoin which they can do now.
Moreover, they could alternatively achieve this through federated server sidechains. In fact, this is the most likely outcome if they choose to bootstrap their fiatcoin on a sidechain. This scheme does not require SPVP because governements will have no interest in being dependent on miners for the security of their chain. Federated models provide far more control and oversight for their fiatCOIN.