I expect 2.4, that's probably they earliest they'll add new tomestones, assuming they come from tomestones. If they come from quests, I'd expect it to be new level cap material, and that's probably an expansion (though they give plenty of mixed messages about that). 2.3 will only be adding Crystal Tower as "endgame" to my knowledge, and we already have some concept art of Crystal Tower armor (based on the bosses), so I doubt we'll get any new gear alongside that.