Lan has been cast.

https://tvline.com/2019/09/04/the-wh...agoran-amazon/

Looks a little young to me. In book Lan was mid to late 40s and was old enough to be Nynaeve's father.

And there is the fact that Jordan was constantly reminding us that Lan had blue eyes as cold and hard as ice, or some such description. I guess he will be wearing coloured contacts.