They aren't be delisted now simply because the current mechanism IS better.
Maybe is better for people who went into debt and are intending to never pay pack and transfer all their loses to others, but not for the ecosystem. Maybe is better for people who is paying their bills with BitCNY to counterparties that are unaware of the peg being lost, but not for Bitshares in long run.
* It does NOT keep/recover peg when BTS price is low enough.
* It's essentially automatic-GS, but not eliminates GS.
As far as Bts is used as collateral, no mechanism on this universe will work if Bts price is low enough. And no, this is not GS Because in GS, positions are taken all at once, thence the 'Global' in GS.
This is different, one position is liquidated at a time and its collateral is shared between all BitAsset holders, who will now have a little less of that asset.
Please think carefully, if you're talking about the idea proposed by Sahkan.
One scenario: assuming there are 1 million accounts holding 1 million bitUSD, when there is one debt position with 1K USD to be forcefully liquidated, whose bitUSD will be forcefully converted to BTS? Unless you mean all of them, technically it doesn't scale well (performance-wise) if considered fairness.
In your example, and assuming Sahkan idea, each of the BitUSD holder will have 0.001 BitUSD converted to BTS, they won't even notice. There would be no GS, No low collateral positions to worry about. It's a pretty neat idea.