It won't really affect anything. Bungie will just remove silver, and we'll still obtain Bright Engrams from XP. It wouldn't be gambling then. Technically, it's not gambling now, since you don't have to spend money to get stuff from Bright Engrams. Even then, you're paying for Bright Dust, not engrams. You can then use the Bright Dust to purchase the vendor sold items that are available to everyone (which is not RNG).