So, first caveat: none of us have seen Immortal difficulty yet, so we're all guessing, obviously. And most of our talk on strategy, at least default, should be for Emperor/Immortal levels of difficulty. 6-7 out of 8, if you will. Diety is usually it's own kettle of fish, and below 6 is usually moot. You can do anything and win.
On Barbs, I think all of us were excited and commented to that effect. On the gameplay we've seen, raging Barbs is Essentially default, and it looks like they will be a thorn. But in no way will devs design a Level 7 difficulty where you need to build 3 military units immediately to survive. AI, for one, couldn't handle that.
So, what we're talking about is whether you can get 3 builds done before needing a few extra units. And I think that likely. And if you can wait until build 4 or 5 to build some military, then you can use your policies and rush them out. And then, while thorny, the barbs are no problem to handle.
Ed Beach said in passing in one of his videos that they recently fixed a bug with barb generation that caused a chance of barb generation on every player's turn rather than once a turn as intended.
There hasn't been a video after that fix that started early enough to compare with the large number of videos three/four weeks ago.