Sounds Great! Here's my idea:

• Gambling site operators will keep at least 50% of all time profit on https://steem-engine.com exchange. Withdrawals are locked!
• Exit-scam happens? Gamblers are getting 50% back for their all time losses! (or gamblers 40%, steem-engine takes10% bonus)

I'm sure steem-engine devs can develop locked deposit feature, we have to talk to them. It may be used as a standard for other STEEM based projects.