From everything I have read from Hodgdon they are completely dedicated to keeping Winchester brand powders strong. When they came out with a new action pistol powder, AutoComp, they released it under the Winchester brand, not Hodgdon. Considering Winchester has only 3 rifle powders and nothing to replace it's fastest rifle powder W748, I highly doubt it will be discontinued.
Then again, they made the same assertions about the IMR powder line but a few months Hodgdon moved most of their handgun powders to the Hodgdon line and announced the remaining, the SR powders, would be discontinued at the end of 2014 so who on the outside really knows?