This post is based on my own interpretation of the dev blog, and is definitely not the entirety of itemization. What remains to be seen of how +skills rework affects pets, artifacts, rings, insignias, and runewords etc could add more layers to building a character

For those who don't want to sift through 25+ pages of a the dev blog, here is a couple key points answered by @Asros.

1) Omega effects (that mechanically changes your skills) will be tied directly to the omega item. (example - Mjolnir will ALWAYS roll with +3 targets hit by lightning strike).

2) There will be 5 RNG seeds from a shared affix pool on each omega item
3) There will be 5-7 omega items per character on release.

4) There has been a engineering request to allow players to be able to reroll specific affixes on an item instead of the entire item. Once you find the Omega item with the affixes you want on it, the plan is to let you then reroll it with a decent crafting cost) to get better rolls.

Veterans

Existing veteran players will still be ahead on the new curve of progression with upcoming difficulty slider. This is assuming 2 things:

1) There will be a reasonable gap between content that drops cosmic gear vs omega gear that can be bridged by the attribute bonuses granted to existing uniques

2) That cosmic gear +1 rework product will not be greater power than reworked uniques, ie. a newer player will not be able to collect random cosmics and progress further than a player with current BiS raid uniques. I suspect that the advantage should also be natural on the existing uniques due to known affixes, instead of at the mercy of RNG.

The 2nd assumption should make players feel better about still playing up to the updates, in that your items will still matter in the "new age", but not remain BiS in the new endgame.

Omega gearing endgame

For item builds: it will be a possible 3 or 4 builds (depending if the last 2/7 omega items appear on the same or different slots). I feel that players will not likely pick talent distributions that will not interact directly with omega effects.

Crafting: The endgame of each build will involve finding the omega item with your desired affixes, and rerolling values. Advantage from that with the current system is being able to roll an items value specifically, instead of rerolling the entire thing. Whether there is a limitation of the # of rerollable affixes or # of times to reroll on a single item remains to be seen.

For balance reasons, I'm not expecting that any of the shared affix pool will be extremely significant, likely distribution of stats we are already seeing on items. Consequence of this is that even across different heroes/builds you are likely still hunting for the same 5 affixes (unless a specific component of your build scales with a certain stat/affix), just on a different omega item.

The current design is for higher item level Omega items to drop in higher difficulties via the difficulty slider.

We are focusing on getting you back out in to the game, playing and getting that feeling of excitement from getting a good drop again.

From this im assuming that as you progress on the new difficulty slider, higher item level gear will drop making your current irrelevant. My only concern is that if you find the perfect ilvl 72 Mjolnir with hp, crit, crit damage, attack speed, brutal rating etc, you end up farming the exact same thing on the next tier just with higher rolls.

This is not entirely different than current endgame item hunt (farming same unique or reroll), but instead of RNG rolling the entire known item, you are relying on the RNG of affixes which could be much worse.

Removal of Uniques

With the Omega items coming, all current uniques will be removed from the game. This is a tricky topic. On one hand, I enjoy the flavor of unique items, and a lot of them definitely seem more appealing after removal of skills points.

However, none of these items really compete with mechanical changes to skills offered by the omega tier. I feel that they would be a good building block of known values until you wait for omega gear of the same item level. Of course, this would add additional inventory bloat, and if not scaling well enough, may not even compete with a weakly rolled omega item based on mechanic change alone. Another disadvantage would be a convoluted crafting system with different rules for uniques vs omega gear.

The future

With this system in place, the future itemization of MH will revolve around the balance and addition of omega items. As they add omega items, it could greatly increase build options so long as there is still proper interaction with talents.

For example, having 8 omega items on a character, with the last 3/8 distributed over 3 slots (2 options each) will net a total of 8 theoretical item build options. However, it is not guaranteed (or likely) that each configuration of slots 1-5 will be a competitive build.

Sidenote: Crowd control

Since crowd control has been announced to be tied with dash, I was wondering interesting ways to integrate it without completely negating this component of combat from the game. In its current iteration crowd control skills provide a very good upkeep time of immunity, but are used reactively on a separate key. If its kept in its current iteration may as well not have CC effects in the game.

Suggestion: @Asros have you guys considered making crowd control an active component of combat, like those games where you have spam a key to get out of a CC? Example would be spamming CC break over 2 seconds to break frozen effect. This would also be a good segway for tenacity to become part of the game again, allowing it to reduce time CC'd or required amount of CC break clicked to break effects.

Another possible way to integrate is to have a moving bar with a certain zone that you need to time a click to CC break. Building for tenacity could increase the area of this "CC break zone"

Thanks for reading! (I feel this wall of text should have @lesotheron stamp of approval on length alone)