Bitshares requires bag holders as well. If everyone decides to get out of BitUSD what next? How well will it "track" the price? You are missing my point. BitUSD has problem with liquidity. Right now if you were to buy and sell a measly $10k in BitUSD within a second what is your spread? What about $100k? So unless there are buyers of BitUSD, it doesn't work. And unless it works there are no serious buyers for BitUSD. See the similarities? You can throw interest, bots and what not at it. But BTSX is not an ideal solution either.
Approaching an ideal is an infinite task. All we can do is keep working on approaching that point (which we'll never reach) and continue getting better in the process. What don't you like about BTSX? I'm pretty happy with it so far and I sense that it's just getting started.
How would you prevent a collapse if everyone decides to sell off? Ask the Federal Reserve what's backing the U.S. dollar. At the end of the day, there isn't anything tangible. Even if it's backed by gold or silver, we've seen that a new generation does not consider those to be the same store of value they used to be in times past. And we've seen that their prices get manipulated by powerful interests in the same way that currencies themselves do.
At the end of the day, what's backing a currency is the people, the land, the resources, the economy, and the utility of that currency. All we can do here is build a powerful BitShares community and financial ecosystem around BitShares. Every song that gets loaded onto PeerTracks, every domain registered with KeyID, every dollar hedged with BitUSD or BitGLD, every tweak to BitShares X that makes it respond better for users, every new user on the forums...these all make our system stronger.
In the end, that strength will stand for something because it's all interdependent and it does things that serve needs for people. That's value, just like the U.S. dollar has value. Its value is a powerful country behind it with a great land and innovative people. BitUSD's and BTSX's value will come from that same strength, only hopefully it will be less centralized and less subject to manipulation by powerful interests. There is a huge demand for a faster, dependendable, and stable online currency, and BitUSD certainly seems to fill that niche.
What is NuBits? A currency. If they build it, will people come? Will it have true value behind it? Time will tell. I think BitShares is much, much further down that road of creating real value.