I'm honestly hoping the Wraithknight is the last of these that we see for a while. Don't take me wrong now. I love the model and the Riptide (the GK baby carrier can go away), but not every army should have the exact same stuff. Armies should offer a unique play experience by having different rules, abilities and models. Making Flyers or Mega-models the next galactic arms race just changes how Codex Creep works. Of the armies not yet updated, Orks are the best candidate for a Mega-model. But they don't exactly need it when so many other things could be added.
"Fetch me another plaything. This one seems to have broken." -Urien Rakarth
Space Marine- "This planet is ours, witch."
Eldar- "No ... This planet is theirs ..."