There is nothing that says that a Market Pegged Asset (MPA) price feed has to be attached to a real currency or commodity is there?
What would happen if we postulated a fictional currency with a desirable price feed behavior defined by well specified equation as a function of time instead of pegging it 1:1 to some market feed? Why not peg it to grow 1.05 to 1 annually and offset the reference currency's historic inflation rate or something?
Thought experiment:
Define an imaginary "Sumo" to have a value equal to the perhaps weighted Sum (USD, CNY, EUR) + 5% per year. Now its price feed relative to that basket is defined in advance for as far into the future as the reference currencies exist. Or perhaps the "Maxo" is defined as the price feed of the strongest SDR currency at any given time +5%.
We could create a "bitSumo" or "bitMaxo" that would behave like that fictitious "dreamcoin" currency and, viola, now we have a currency that will always outperform a specified basket or the best fiat currency by 5%.
Just dial the equation into Xeroc's bot to keep your favorite artificial currency collateral topped off to its completely predictable performance relative to the price feeds of it's poor, hapless, fiatic competitors.
Why track poorly behaving fiats and commodities when you can dream up you own ideal coin behavior?