You can have your BTCs in bitBTC, instead of OPEN.BTC, and if Openledger disappears, you can still change them to bitUSD or BTS.
Either way this is an obvious problem, and the only satisfactory solution would be to have a FIAT P2P exchange.
I proposed to talk to Bisq, a P2P exchange
https://bisq.io/ for this, but it does not seem that the people of bitshares really liked the idea.
https://bitsharestalk.org/index.php/topic,24703Another solution would be to implement that functionality in bitshares, but I do not know the legal implications, perhaps an external solution would be better.