Patch 2.3 is coming for Diablo 3 and it looks to be a hilarious increase in player power. The main thing that will accomplish this is Kanai's Cube, which allows players to destroy legendary items to place their powers in the Cube. They can then select 1 weapon power, 1 armour power, and 1 jewellery power to permanently augment their character.
So, for example, I could take my darts based witch doctor and add in Starmetal Kukri (~60% damage boost), Convection of Elements (40% damage boost), and Mask of Jeram (~80% damage boost), all of which multiply for a whopping 300% damage boost.
I can probably find more awesome things to do that are even better, but this gives you a vague sense of the magnitude of this buff. The huge thing it does is vastly increase the number of permutations available to characters, especially those using big sets. Being able to sneak in a single item in any of those formerly locked set slots is monstrously powerful. I suspect that Witch Doctors will actually benefit more than anyone because they were so dependent on two insanely overpowered weapons and a bunch of build defining helms that adding in one more each of those is far more utility than any other class gets.
Generally I think this is a great change. Part of the way these games always end up playing out is gradual power creep and that is just part for the course - you do this so that new records can be set and so that bug fixes or nerfs don't eventually leave some records unbreakable. Even if it weren't part of the unavoidable power creep I would enjoy this change greatly as it opens up a ton of new and interesting options for play.
There are lots of other things too, like new items and new set benefits. I may play my current Darts based Witch Doctor for awhile, but the new Helltooth set looks completely bonkers and I will definitely want to try that out. I suspect Blizzard is going to stick with their plan that the huge sets are totally brutal and you have to be using one to be remotely effective, but at least now we have a lot more ways to work around those limitations with the new Cube.
I haven't played much D3 in a long time but I am pretty sure I will give it a spin when this patch drops so I can test out all the new shinies.