Here is a breakdown of what is coming for the Old World and more importantly when. The ruleset is likely to be based off of 7th edition rules with a starter set pitting Kislev against Chaos.
via a source here on Faeit 212
We will see big announcements next year. The core rules are completed for some time and they pepare the books for printing. When everything is working as planned we will see the first two Minatures at the upcoming Warhammer Fest in April next year and possible the release announced for 2024.
The Ruleset is mostly based on the 7th Edition. No rules for massive units like in the 8th Edition. Like in Age of Sigmar, the Profiles of Monstrous Creatures and similary Units get worst when they lose LPs. Commanders and Heroes get rules to customize them more.
Also other details:
The planing of Warhammer: The Old World began in August 2019 and a release innitial was set for mid 2023 for 40 Years of WHFB, but then covid...
All armies get complete new ranges of miniatures. Two Armies for the Starter Set (Kislev and Chaos). As earlier said there will be "Compendiums" for owners of old armies with all units the factions had in the 8th Edition before Endtimes. Veterans will only need their certain Compendium and the Rulebook.
Releases will come in yearly "Circles" - an Army Set with one faction, Armybook and over 12 months some seperate boxes of core units in plastic (GW) and the rest in resin (FW) for this - then the circle begins anew with a new faction over other 12 months.... Exception will be the first "Circle", which will see the release of three factions; Kislev, the Empire and the Forces of Chaos.
Original they planned to start with The Empire and Orcs and Goblins, but this was discarded.
No plans for a "second Edition" after 3 year so far.