Yeah I don’t see that being an expansion that’d have technically 4 major patches (11.0-11.3) with 2 minor patches between each.
It needs more variety, which is why it would inevitably delve into the cosmic stuff.
At best the only way I’d see the light being a semi-main antagonist would be in a “Light vs Void” expansion where there’d probably be a patch where you’re fighting some rampant Naaru and/or a reformed Scarlet Crusade.
Because the ship for Yrel coming to Azeroth has sailed.