https://www.youtube.com/watch?v=qPsCGvXyrP4 On cc price stability: From 01:20:00 on price stable cc. The approach he mentions works about like this: The protocol issues more coins if price goes above the feed price (USD feed for example) and destroys / buys back coins if price goes below price feed.
There are two currencies: A stable coin and a volatile coin. In case it is necessary to increase stable coin supply, stable coins are auctioned of for volatile coins.
In case stable coin money supply has to shrink the auction is the other way around (volatile coins auctioned of for stable coins).
The above is from Vitalik's talk. Here is a more detailed whitepaper:
https://github.com/rmsams/stablecoins/blob/master/00-main.pdfOn POS: Vitalik turned a POS fan. Not much new, except for 01:08:00 - 01:10:05. But overall not yet that well thought out.