The only real way to solve DPS queues

[Shurrikhan]

I am yet to play a game where the removal of the holy trinity truly worked. Guild Wars 2 tried this and to be honest it was a complete failure in my eyes.

I mean if they pulled it off, sure however I would be more inclined to go for a spec tree system, which allowed a job to spec into one role or the other. However this is just flat out too much work for this game in my opinion. You would also have optimal build paths and you would likely end up in a similar situation to what we have now.

Honestly, you don't even have to remove the Holy Trinity in order to avoid its stagnation to some extent, especially its contribution to tunnel vision and toolkit waste. You just need to adjust certain underlying mechanics, such as through reforms to mechanics like enmity (and/or to mob AI); perhaps by expanding mechanics like damage splitting, interception, or active dodging; and to add certain mechanics that can place soft windowed or situational limitations to a tank's uptime such as natural vulnerability stacking (e.g. XIII's "chain gauge" as able to affect players as well, and likely stacking slower on tanks than dps, allowing DPS to tank briefly without being overly independent or powerful generally and tanks to still make use of some DPS "snap-tanking"); or rebalance versatility in regards to simultaneous output (mitigation and damage) or functionality (survival and damage-dealing) in a different way, such as damage-based interruption (towards both enemies and allies, making DPS more capable and culpable in regards to survival) and resistance to interruption (probably significantly higher in tanks than melee than ranged than casters, such that a DPS doesn't necessarily have to be one- or two-shot by a mob for a tank to be worthwhile, as the cost can also be in part its damage-dealing).

As for the implications on dungeon-running, this need only extend a bit further—adjusting AoE formulas, as not to so soon or so effectively habituate massive pulls.