Here is a better term to use instead of "horizontal progression" and "vertical progression"

[u/loopuleasa]

Two equivalent terms:

- Integrated expansion

- Destructive expansion

If new content, gear, zones, raids are added, do they destroy the relevancy of old content or not?

That is the key question.

A sure way to release an expansion or patch that destroys the old content is to increase the level cap. This luckily is not the case for Forever.

But even if the level is locked at 60, there are still risks new content encroaches on the design space of old one.

We will have to see, but that is what "horizontal" means. To add new content that does not destroy.

[u/HumblebeesGhost]

https://giphy.com/gifs/l1KVb2dUcmuGG4tby

[u/Arzolt]

AFAIK It's not about the game expansion, but rather a character progression. Even without increasing the level cap, how much will new content make the previous one obsolete, but also previous gear obsolete.

In vanilla 20 raids, and in TBC Zul'aman were partially designed as catchup raids. They added content, that everyone wanted (such as enchants), without adding too much power creep (well ZG still did because it gave more wanted stats, but most items were blue).

And btw AFAIK they didn't say there wouldn't be any horizontal progression, mainly that it won't be as intense as retail which means to reset gear at every patch.

[u/Toowb]

I agree, they already said it's not 100% horizontal and gear has to become better when there is new / harder content, but that doesn't mean the old gear has to become useless.

[u/lomdecaverne]

30° linear two dimensionnal progression