Bob,The CBOE Futures Exchange (CFE) offer the VX futures while the CBOE options exchange offers the VIX options on the VX future. Both are cash settled and there is no cross margining for customer accounts as the NFA/CFTC regulates futures and the SEC/FINRA regulates the option markets for CBOE options. With regard to VIX options, OI has nothing to do with depth and liquidity of those markets. All that matters is if the Market maker can hedge the trades. By the way, the VX future is 10X the size of the VIX options. The VX Future is $1000/Point while the VIX options is $100/Point.
The way I have always understood it, the VIX options aren't options on the VX future. They are options on the VIX index. Both will settle for cash and you can use the VX future to hedge as they settle to the same thing (although cross margining is a problem as you mention). Similar to the SPX index options and the ES future. Although the ES future has options on the future itself, unlike VIX.
This is an important distinction as it allows the VIX options to be SEC regulated vs CFTC regulation on the future as you say.
