I do like the idea as you are right people love to speculate. Probably could bring that over to that bitcoin betting site that lets you bet on everything forget the name of it. You could still speculate if you wanted to "add" to the bitcoin business's deposit amount because you have confidence they will remain. Maybe in return , if they are there 6 months later you get the excat amount you put in 1 to 1 - so you add 10 btc to the 100 btc the business put up. In 6 months, you get 10 of that 100 btc for being right and the company has to front another 10 btc thus you start seeing a community rallying around the success of a company. Good thinking!
I don't think the business would even need to put up money. A person that opened an account with a bitcoin financial service company wants to insure their money. That person just wants to lower their risk. A speculator is willing to take that risk in return for a potential profit. The "insurance company" makes standard contracts that expire every quarter. They can also help out their customers by rating each company to give their customers a better idea of the solvency of the company. Some people may not get insurance, but if they get burned by a scam company everyone can say, "you should have gotten insurance!"