Depends on how those world bosses play out. Allow me to explain.
I highly doubt Blizzard are going for a hard encounter similar to raids in an MMO, or anything that resembles Greater Rift composition from D3.
From what I can tell, they are going for something similar to world bosses in Marvel Heroes or world quests from WoW (the ones introduced with the Legion expansion pack)
Personally I’m a big fan of D2:LoD, and I am generally against WoW features in Diablo, but I really like the idea of mixing Marvel Heroes (which is basically how David Brevik would have made D3) and world quests from WoW. I do believe this fit very well into a Diablo setting.
Considering, that you could solo world bosses in MH, I think the same would be possible in D4, but we’ll see.
I don’t believe so. Again, you seem to envision these in terms of raid encounter from WoW. I don’t think Blizzard are going for anything like that and more along the lines of world bosses from MH and the world quests from WoW.
I did world quests back in Legion and they worked damn fine.
I don’t believe these wolrd bosses will be a big deal in terms of being difficult to do.
Actually, the boss difficulty has nothing to do with Gr meta with support and DPS classes.
The Gr meta with supports emerged due to the simple fact, that classes had (and still have) very powerful offensive buffs. In early seasons it used to be 2DPS, 2 Supports, and later on even 3 supports. It also emerged because of the lack of balance when it came to different DPS builds.
If the characters don’t have such powerful buffs in D4 to begin with, then there wont be pure ZDPS support builds, and thus support meta.
I believe whatever buffs the characters in D4 have will be more along the lines of D2 auras, druid spirits and barbarian shouts… and by that I mean, those buffs will be good for you to use for your solo build anyways, and not just useful on a pure ZDPS support build.
I highly doubt they’ll have ZDPS builds in D4. I just don’t see them having D3 type of buffs (or 2 min cooldowns).
But hey, even if there were must have skills for world bosses, you do realize, that you’ll be able to farm and/or trade for skill books, and max some skills other than just the ones you use for solo, right?