Do you think it's possible that fiat $10,000/USDcoins2 colored coins redeemable for either $10,000 OR 100 bitcoins would be economically feasible?

Sure. And once USDcoins are available USDcoin call options are possible, as are all the various permutations of security constructs you can think of. It's just a matter of having someone to bet against.

The issuer would be spending to achieve a stable exchange rate, which may be important for clearinghouses, banks, or individuals with savings.

I don't think the issuer spending to try to force the exchange rate to be stable works too well. It would be better if the issuer is paid an appropriate premium for the issuing the option and the purchaser paying them for what amounts for insurance against a large risk. (And instead of 'better' I could also have said "outright inevitable if crypocurrency use becomes widespread".)