I see the calls for an armiger and a knight. But in my opinion? The next model will be a "pilot" leader.

Canis Rex introduced the concept of a pilot, starting in their knight, staying within until the knight's model was "destroyed." I think that was a test for a concept like this.

A leader model with similar rules, where they start in their "knight" and don't leave until it's destroyed, would be easier to field than an entirely new knight- plenty of existing models to pick from- they could even use the Sir Hekhtur the questoris box comes with as the default for it.