Ezra is certainly a theoretical possibility, especially if he's going to have a role in what seems to be an ongoing quasi-adaptation/retelling of the 'Heir' trilogy. Hard to say how well that would fit into his character arc until we see what Dave has in mind, so we'll just have to wait and see.
That said; not sure I buy the idea of Palpatine ordering Ezra's death the way EU Palps did for Luke. Last anyone saw of him, he vanished over Lothal with the entire 7th fleet. By the time of RotJ; so far as The Emperor was concerned Ezra was old news, long gone, and seemingly never to return, probably dead.
In the original story; part of the whole reason Mara struggled was because it wasn't just any old order, it was a psychic imperative imposed upon her psyche by a Sith Lord through the force as he was dying; which don't get me wrong, it a dumb concept and probably not how the force works. Still, that's a far cry from some old termination order for a target that's been off the map for half a decade before Sidious died. Doesn't quite have the same sting.
A modern re-interpretation of that struggle should probably be more akin to left-over Manchurian Candidate/Winter Soldier style mental conditioning, which he did seem intent on using on
his first attempt at raising force sensitive spies. It's fair to assume he'd do the same with his assassins.
Anyway, I merely proposed Starkiller as a possibility because bringing them both into canon as a unit/duo solves a lot of the inherent problems of adapting them separately.