One idea a few friends of mine have mentioned would be similar to the reward system from delve. You kill an NM and unlock the ability to purchase all the items that particular NM drops. Although it will take time to farm the currency to buy these items (whether it be plasm, cruor or what have you), it would bring life back to VW. It would also open up multiple paths for people to acquire the HM or any other items they may want (excluding pulse cell items IMO).

From that, if they were to decide to use cruor as the means to purchase the items it would keep voidwatch active because it is still the fastest way to get cruor. SE would simply have to scale the prices of the items based on how much cruor you can get per kill of a VWNM.