The Horizon multiplayer should have been like Ghost of Tsushima Legends
Ghost of Tsushima had a full, excellent story mode and then later added a multiplayer version called Legends. It was almost all co-op PvE, with a small amount of PvP. This is what I think the Horizon multiplayer should have been.
Once the new game comes out, they switch the majority of the development team to work on "Horizon Legends", a faithful, canonical version of the game that sees players team up and perform missions (and a series of missions in small story arcs), survivals and PvP.
Players would be able to choose from a set of character archetypes and level them up, customise them by way of acquiring and levelling up new gear and customising their appearance. Every player would be able to play as all of the archetypes.
The maps and areas from all of the games and DLC's would be used (although only portions of each map for each particular mission).
I think this would be more in the spirit of what was initially intended with the plan for in-game multiplayer and far more fun than the Fortnite cartoon we are getting.
This upcoming multiplayer might be great fun, but I think that to most of us it feels like another attempt to drain our wallets as much as possible.