Will there still be an Xbox Elite controller in the design of the new Series X / S controllers?
What do you mean by design? In terms of color, it fits quite well.
But seriously: Since the Elite Controller 2 is fully compatible and has no functional differences apart from the missing share button, Microsoft sees no reason to rush.
However, it is not unlikely that, after Elite Controller 1 and Elite Controller 2, an Elite Controller 3 will appear in the near future. As far as I know, this is still unconfirmed.
Yes it will.
As usual, Microsoft will bring out a new Elite Controller for every new generation of consoles.
This year's one will probably have the new share button, the "new" design and the new ergonomics. Great, however, will probably not change that much, except that it should have adaptive triggers, similar to the Playstation 5 controller, only worlds better and more sophisticated.