Disclaimer: I'm not a theory crafter, hardcore raider, have seen the new patch or anything. I'm just an average gamer, doing a bit of trial and dungeons, and seen some Elsweyr's leak information here and there, so take all this with a grain of salt.

From the OP-ness of the spider synergy this patch, to lots of sets that proc on synergy next patch, I think ZOS is moving from "everyone wear the same sets that give you 50k dps" to "everyone wear different sets that only do 40k solo but when synergy them together in a group your group dps will increase significantly". If the meta really heading that way, then I love it. It feels more like you are part of a group rather than just "people who attack the same target". I always love to play crown control and buffer/debuffer in other games. It feels unique when only you can provide a buff to the group. Years ago there was the Morag tong + NMG buffer but it's been long gone. Hopefully Elsweyr can bring back the buff/debuff role and shift some of the weight from tank and healer.

However, for it to work, the new trial must be designed for the group to stay in range of each other. If the mechanic requires people split up to groups of 4-3 or even lesser more than half of the time like in Cloudrest (portal group), people will just stick with sets that can do 50k solo. Now I have not seen or know anything about the new trials yet, except it has 3 bosses and you can do HM on each of them. But I hope ZOS can bring back the buffer meta and bring it to another level with all the new sets.