The next edition of Warhammer 40k may not be the paradise for melee armies that early previews hinted at, if the new rules previews for the T'au Empire are anything to go by. Games Workshop has revealed a trio of new detachments for the blue-skinned xenos, and it seems the T'au will have a plethora of high-tech tricks to circumvent the advantages being granted to their more hands-on adversaries.
Warhammer 40k 11th edition promises to be a much more hospitable environment for melee armies in several ways. The new 40k terrain rules and recommended deployment maps add more obscuring terrain to the game, reducing fields of fire, while objectives are now inside area terrain instead of out in the open. The benefit of cover penalizes enemy accuracy rather than improving armor saves. Critically, units inside terrain that didn't shoot last turn are Hidden, and can only be targeted by enemies that are within their 'detection range', which is usually fifteen inches.
Thanks to 'For the Greater Good' and Markerlights, the T'au Empire can already circumvent the improved Benefit of Cover - but the T'au really don't want to get within fifteen inches of the enemy if they can help it. Fortunately for them (and unfortunately for all the other Warhammer 40k factions), two detachments revealed on WarCom on Tuesday have ways to increase detection ranges.

In the Auxiliary Cadre detachment, Kroot and Vespid units can 'prey-mark' an enemy within twelve inches, increasing detection range against it by three inches. In the Advanced Acquisition Cadre detachment, the Unmasking Suite upgrade - which can be taken by up to three Ghostkeels, Pathfinders, or Stealth Teams - lets them increase the detection range of an enemy unit by nine inches.
The T'au Empire already relies on Markerlights and Observer units as force multipliers for the rest of the army, and it looks like these units are going to have even more responsibilities in the new game. That's going to make them a higher-priority target than ever - and to match that, both new detachments also increase their survivability against enemy firepower.
In the Advanced Acquisition Cadre, the Expert Fieldcraft rule allows Pathfinders and Stealth Suits to remain Hidden even after shooting, while the Autoreactive Camouflage stratagem grants Hidden Pathfinder Teams and Stealth Battlesuits +1 to their armor save in the enemy shooting phase. In the Auxiliary Cadre, Kroot and Vespid units can shoot and remain hidden while within six inches of Ghostkeel or Stealth Battlesuit units.

There are new toys for T'au commanders who care more about the payload of their guns than the delivery system, in the reworked Experimental Prototype Cadre detachment. This increases the range of Battlesuit Character units' ranged weapons by six inches, and has enhancements and stratagems to increase their damage output further.
Happily for Blood Angels and World Eaters players, nothing has been revealed so far that will make the T'au any more survivable in the Fight phase. When the remnants of your army make it through the wall of T'au firepower and into melee, you will still reduce them to little blue chunks.
Do you think these new options are going to make the T'au more viable in 11th edition, or will the prevalence of obscuring terrain render these advantages moot? Let us know what you think in the Wargamer Discord community.