The only way I'd accept Lang is if he is/were a side character and of roughly the same age bracket as Pym. Marvel like to micromanage their movies, so I don't think (hopefully) Lang will be made a major player and an Avenger to boot.
I'm staggered that there's still uncertainty whether A-M should be mainly about Hank + Janet. Like I said in another thread, if Wright - even though I like his style and it would suit an A-M film - is insistent on making Lang the main player, someone else should do the movie.
Things are looking mightily grim.
We may not get Ant-Man & Wasp into TA2, and - going by the current situation/hearsay - even if they did make it, it could be Scott ****ing Lang as Ant-Man and who knows who as the Wasp!