I was actually giving it some thought the other day... maybe this isn't the proper thread for it, admins let me know if it's the case... but I was kind of at loss to see what could/should/I wanted to see change as far as our model range was concerned. To me the Terminator/Paladin kits are really cool as is, with lots of weapon options and quite a few customization options and extra goodies. Same goes for the standard power armored Marine kit. A character kit or individual/specific character models for the Brother-Captain, Grand Master and Brotherhood Champion would also be very much appreciated... I mean if we're being honest the "Brother-Captain" and "Brotherhood Champion" models are really just the Justicars from the old metal sets. Other than that though, and without creating a whole unit(s), I was kind of stumped. Maybe a specific Purifier box, with more detailed armor (something along the lines of Guilliman's armor if you see what I mean) and flaming weapons or something?
Any thoughts? Again, specific to the model range itself, not rules-wise.
Well, that's not fair, constraining the conversation to models in a thread about books. So let me break your rule and try to address concerns about rules and models together.
Everything I'm about to say is pure speculation, please don't confuse it for a rumor but do tell me how far off I am.
GW publishing has become fond of patterns. The Psychic Awakening books followed a pattern, 3 or more factions in each book with new rules, stratagems, relics, points adjustments for each. As a bonus, some factions got new models.
With Book of Rust, we're seeing a new pattern emerge: 3 factions, new rules / stratagems / relics / points for each, and some factions got new models. It's entirely new and a big change from Psychic Awakening, where the pattern was pretty much identical but had a different name.
Which bring us to the question of models. GW did not release models alongside Book of Rust - they released models alongside a Codex that happened to come out at the same time. My guess is this is the pattern we're going to see going forward.
My guess is there will be 3 Codexes announced within the next few weeks, one of them will be Grey Knights (based on the rumor in this article), and the next volume of Book of Rust will follow soon after. With the release of the Codex, we will know about new models.
My guess is that GW decides to allow Grey Knights to take stuff from Codex: Space Marines / Codex: Astra Militarum, with some restrictions. You have a good point, Grey Knights have a lot of unique characters and creating a new one might be a struggle. GW could fill more gaps by letting GK take, say, a Primaris Dreadnought than they could with another baby carrier. Likewise, something that has been missing from GK armies for a while now is Inquisitorial Guard. Giving GK robust amounts of meatshields and cheap tanks could do more for the faction than any other changes.
These are just guesses, I don't have any particular insights except to say GK don't really need new models. Technically, the faction overall is one of the youngest in the range. I'd be happy to see something new come along, but I'd be happier to have something that plays more like the old Daemonhunter's Codex. Based on the Deathwatch treatment, feels like GW might be looking at it the same way.