I'll just elaborate on what I wrote on the top
Normal dungeons : Give blue quality loot, JP and VP. All bosses have chance (low) to drop LFR quality epics for all slots.
Heroic dungeons : Give LFR quality or lower loot. Primarily focused on raiders. It's very very difficult and requires premades.
Scenarios : Same as dungeons except it does not have fixed item table. Something like unlucky streak prevention could be implemented to offset too much RNG
Dailies : Doing the daily quests give JP and VP. You can buy blue quality items in lower reputation, and progressively give better rep rewards as you get higher. If you reach certain reputation they give you special quests to give you normal quality epics. Speed is significantly faster compared to mop (you can run 3 days a week without being gimped too much)
Weeklies : Same as dailies except its once a week
Professions : You can craft account-bound epics. Since they cannot be traded with other players the crafting will be cheaper and faster compared to boe ones. You start from basic item, and items have "craft upgrade" that is similar to item upgrades but require different materials and have weekly cooldown. So for example your item would start in 0/10 craft upgrade, every week you can have 1 upgrades until you reach 10/10. Boe epics remain but require extra work/mat and generally are very expensive to make.
Grinding : You can grind mobs, get reputation or turn-in items which can be traded for epic items or JP/VP. Or other grinds could give you boa materials which you can use to craft epics.
Treasure-finding and Rare-hunting : The world bosses and rares have chance to drop from blue items to LFR/Flex/Normal level epic items as well as pets/mounts/heirlooms/toys. Should be more unpredictable.
Points : JP and VP can be gained by doing almost any activity (so you can do whatever you want to cap points). JP could buy blue quality items and heirlooms and other miscellaneous stuff, while VP will give you normal raid quality items.
LFR : Same as now, except it will feel significantly less forced on everyone
Quests : you get epic questline which takes long time, it gives progressively better reward until at the end give you normal quality epic of your choice. So extension of class quests in vanilla or lower version of current legendary quest.
New tier comes out and you get whole new set of above. If they really extended dev size these should be absolutely doable