The Forgeworld books have run their course? well they apparently have and new books are being worked on to replace the rule sets you have. Here is the official announcement.
Since it would be high unlikely to get new Forgeworld books and then a new edition to 40k 6-8 months later, it seems likely that this is a solid hint that the rumors of a new edition coming for 40k mid year are likely. Interesting.
via the Warhammer Community
https://www.warhammer-community.com/2020/01/24/new-rules-incoming-for-forge-world-modelsgw-homepage-post-2fw-homepage-post-3/
Well, we have good news for all lovers of Forge World’s resin miniatures – new rules are on the way for these incredible models.
The Warhammer 40,000 Studio – those industrious people behind rulebooks, codexes and expansions like the Psychic Awakening books – are hard at work on a new series of tomes that will cover the range of Warhammer 40,000 miniatures Forge World produce. These books will include updated datasheets and army rules that give these glorious models abilities and benefits that are comparable to the rest of the forces in the game.
This means that the current range of Imperial Armour index books – which launched in 2017 alongside the current edition of Warhammer 40,000 – will be riding into the sunset. We’ll no longer be printing these volumes, so when the current stock is sold out, they’ll no longer be available. If you want to use your Forge World models for now, you should grab the relevant books while you can.
The datasheets in each Imperial Armour index will remain official until new rules are published, so the books are still your go-to option for getting your miniatures onto the tabletop.
If you haven’t checked out Forge World’s range of Warhammer 40,000 models, head to the Forge World website now and take a look at miniatures like the Leviathan Dreadnought, Gargantuan Squiggoth, and the truly astonishing Warlord Titan. Pick up your favourites, grab the appropriate Imperial Armour index, and get playing!