IB discusses all of this on their website, in detail. All you gotta do is go read it. But, your main account with IB is called the Universal Account...it's a securities account. It's insured by SIPC and Lloyds. But, if you make a trade in a futures contract, for the period that you have that trade on your margin will not be insured. SIPC does not insure futures positions. Go to their website and read about it. OldTrader
If the account is segregated funds, in theory it should not disappear even when the company dies, because the money is segregated from the company