@VisionOfScarlet on Twitter posted this wonderful breakdown in her feed about the instances of Paul Bettany indicating he is in Avengers 4. She mentions an interview she doesn’t have the source of, which may be this one.

Now, it is possible (as the OP mentioned) that these are older photos, and there’s also the possibility of reshoots and misdirection… but this is everything I know of so far that would indicate he is in Avengers 4. Take it to mean what you will.