Games Workshops Teaser video says it all
Three new Knight Variants, rumoured to be the Galant, Crusader, and Warden. These are all names that older players who dabbled in Epic/Titans in the 90's would remember fondly.
Traditionally a Knight Crusader is a long range weapon platform with two main weapons, a twin linked lascannon and a Quake cannon (think Strength D artillery). This time around it appears to have a Quake cannon (on the right) and the battlecannon from the Paladin/Errant as seen in the image above.
I can find very little on the Knight Warden's armament, but they appear to be pilots who are no longer in their prime, or ready to retire. Slower than a regular pilot but with more experience and wisdom, they are charged with defending the Knights household. I believe they will have the power fist/Quake cannon armament as in the first picture.
I can find nothing on the Knight Galant, but I do remember something from my time playing Epic. Pretty sure these where dedicated close combat Knights hence the chainsword and powerfist combo fitting.
What I do find interesting is the image profiles. They appear to be based on the Paladin/Errant chassis, however with a different carapace. I would expect to see the original sprues supplemented with a new one with the three new weapon systems, and new carapace + accessories. It will be interesting to see if the carapace mounted missile launcher will be reconnected as a n option on the Paladin and Errant.
Also rumoured to be coming is a new Codex for the Knights and new Datacards for the first time.
With these additional new variants, and rules it appears Knights will be making the jump to a much more rounded and balanced force. I expect to see upgrades, wargear and ranks for all the knights similar to what is found in Book IV of the Horus Heresy! Alongside the imminent Warlord Titan release, this is going to be an expensive month for me...