Storm Island VIP Discount Duration?

Does anyone know if/when the VIP discount will expire? If it has no expiration date, how would it work if it was ever part of an Xbox LIVE sale? Say the LIVE sale was also 50% off. Would it then be a mere $5 by being reduced by 50% twice?

Sorry if this has been asked before and I didn’t think it fit exactly with the other threads. I’m curious because I haven’t seen any details or stipulations in any news articles about it yet.