You need to ask them if they are going to port it and request info about license policy, because Phpfox V2 stable will only be available at December. Most modders will start to develop mods until they can test/study the stable version, which means you will only start to see most of the V2 modules out by Jan/Feb next year.
Aitoc have never stated which of their mods will be ported to V2. If we look at the usergroups permission and subscription system in V2 already, I dont really see a need for Aitoc to spend months recoding this mod as this element is robust enough in V2. A better strategy for them might be to take the e-commerce element from this mod and improve on that for V2.
And maybe if phpfox cant get CCBill included by stable they can port this payment gateway class over.
And no they don't need to stop selling it there are still alot of people using 1.6. Maybe you need to research what's already in V2 a bit better before making statements like this!