Blizzard have talked about changes coming to Diablo 4's itemization

In a recent post on the game's official website, Blizz have talked about the changes coming to D4. They agreed that D4 needs more character custimization options through deep and rewarding new items (“Easy to learn, difficult to master.”) and they also want to make the itemziation in D4 unique (take the best parts of past titles and improve unpon them, but comepletely copying D2 or D3 isn't an option, "We don’t want to create an exact copy of Diablo II or Diablo III").

They have also talked about the new affixes coming to D4, and while looking at some of the criticism previous systems received, the team came with some potential solutions:

We’re increasing the total number of affixes on items, including Magic (Blue), Rare (Yellow), and Legendary (Orange). This should raise the overall importance of non-Legendary affixes on your character’s overall level of power.

We are also introducing three new stats: Angelic Power , which increases the duration of all beneficial effects (like self-buffs or healing) Demonic Power , which increases the duration of all negative effects (like debuffs or damage over time) Ancestral Power , which increases the chance of on-hit effects (aka increased proc chance)

Each of the three Powers will have a list of affixes that are attuned to it, so depending on which stats you care about, you might want to focus on Angelic, Demonic, or Ancestral Power. In the examples above, you would need 50 Demonic Power to get an additional rank in the Devastation skill, 55 Demonic Power for 25% Fire Resistance, or 60 Demonic power for an additional 2 ranks in the Char to Ash skill. If you wanted to build around Crushing Blow, you’d need to stack at least 55 Ancestral Power instead, while 40 Angelic Power would be required to gain 25% Cold Resistance.

Also they've decided to remove D3's Ancient Legendaries and instead introduce a new Legendary consumable item which would allow users to add a Legendary-affix to a non-Legendary item.

In our last post, we mentioned that we were looking at some potential changes to Ancient items based on your feedback. We are going to remove Ancient Legendaries from the game in their current form entirely. We will be introducing a new type of consumable item (which we haven’t yet named). This item would be earned by killing monsters, just like other items. It would have one random Legendary affix on it, drops only in the late endgame, and can be used to apply that affix to any non-Legendary item. This means a few things: We create an “elective mode for items” that is experienced after players have had time to experience Rare and Legendary items normally, as well as familiarized themselves with a variety of affixes

This adds a way to introduce new methods of play without adding even more power to endgame items

Rare items with the best affixes on them are always useful and retain value

This being said, all of this is still WIP and probably Blizz take players' feedback to heart.

You can read the full post here.