It is not surprising at all that SE basically said they won't ever be making alliance content. I'm gonna take a wild stab and say they probably won't make any really challenging content, either.

There is zero incentive to do Alliance content. I have done delve in a 5 man (2 mules) group and done it with 18. Doing it with 5 I left with ~10 merits, half a job point, 110k plasm, and 1/3 the selling price of a Bole/Pelt/Claw/etc. With 18, you leave with negligible/no merits,fractional jp, the same plasm, and 1/18th the selling price of the craft item. Low man groups can leave with enough merits to jump right into a high tier mission battlefield, while the 18 man team has to go farm those merits in addition. In 18-man Bosses spam frustrating TP moves (Timber/Firefly/Dream Flower/Frond Fatale/Deracinator just to name the Yorcia zone) vs seeing them far less frequently in low-man. Even if you try to subvert the amount of tp moves they do (e.g. reduce tp-feed), you still have to account for ~800k additional HP on each NM. That leads to everyone hitting hate caps quickly and the boss running around randomly attacking everyone. In all, it leaves a bad taste in the mouth. Frankly I would rather they rework tired mechanics and fix current content than to feed us more of these poorly designed and rewarded content for alliances.

In any case, "Alliance Content" is an unspeakable term in this game these days. Just like "Hardcore Play" and "Teamwork." They have been redefined and replaced with terms like "Low Man", "Job Points Botting", and "Summoning Trusts."