Sounds a bit like protocol design 
. Some interesting roperties:
- payable in xtz
- decentralised: Maker model sounds clever. But how to know if the price feed is incorrect(compare deviation?)? And how to punish bad behaviour (slash stake?)?
- should have some reputation mechanism or forbid anonymity: coinbase is far less likely to manipulate price than a long term good behaving anonymous quote supplier.
Many questions remain:
- how to determine fee?
- is quote an average of all feeds, or median, or…
- should the quote also include a confidence level?
- if confidence level is too low, should quote even be published?
- …
