The Ascians going forward

[Hainiryun]

With regard to what the black masks are up to these days we haven't heard anything of them since 5.3 (as far as I can recall anyway) when there are a few offhand mentions of them spreading chaos around Norvrandt during the star shower, and being dealt with off screen by our allies.

As for whether they could be a threat going forward, maybe? We've already seen a group of them try and fail to get revenge on us for defeating their overlord way back in the HW SMN quests so they'd likely struggle to threaten us personally unless they came in force. But that requires someone to organize them, with some overlords still unaccounted for (someday we might see Halmarut again) they'd probably make more sense than individual black masks taking over.

Could they pose a threat to people who aren't us? Probably but only really in ways that would feel kind of unsatisfying. If a major combat capable NPC got taken out by a black mask it'd probably feel weird even if they had the element of surprise on their side etc because we've already established at this point that a competent NPC can take these people on. It'd feel equally weird if we suddenly find out that F'lahmin got ganked by a spooky wizard out of nowhere while we were off dealing with something else.
Summoning as a threat feels like it's largely worn out its narrative relevance at this point between the cure for tempering, warding scales and general diplomacy disincentivising summoning. It could still come up again but it'd have to be somewhere we haven't been before to really cause much damage.

Honestly I think they were dropped largely because they aren't really necessary at this point in the story. We've been going toe to toe with the overlords for so long that it'd feel arbitrary to suddenly have a random lower tier mooks causing trouble on a large scale. It also sort of provides a reason why we personally haven't seen them for a long time. We're a threat to the actual overlords so there's not a ton to be gained by them sending their minions into the meat grinder when they could be better employed elsewhere. Elidibus didn't send them to fight us because they weren't capable of stopping us and he wanted to deal with us himself. The 5.3 mention is that explanation for why they're not around anymore IMO. They still are, they're just not engaging with us directly because that ends badly for them and doesn't achieve much.