If you are talking about a 1:1 peg I don't see this, really. If it persists then people will just flee the SC and it will become irrelevant (absent some short term uses like paying for coffee perhaps).

If you are talking about a non-1:1 peg then it isn't clear to me that scBTC need necessarily be worth less than BTC. For example scBTC could pay dividends in some non-convertable asset.