Sub price for 4 to 6 months is equivalent to the battle pass (it can be broken down into monthly access payments)
Gives access to the newest patch cycle content, expansions would no longer be core progression of the story.but standalone patches which act on azeroth / other worlds / planes we have already visited. So basically cataclysm treatment in 6 month cycles, which you pay to have access to. Access would include typical benefits of a subscription, but the f2p model would become less restricted for someone not wanting to do the most recent content, such as
New pvp season
Newest raid
Latest zones to be revisited in the patch cycle.
It wouldn't necessarily be a do away with expansion developments, but a time in wow where the story ping pongs around the map twice a year to round off edges that don't deserve an entire expansion to explain but still deserve growing before wows story develops deeper into cosmic forces