@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.

garbaegee:

Hello can get a reservation for my funeral and please send the bills to Marvel Studios

Mm… I’d believe it if they hadn’t said the dusted Avengers are permanently dead too. That’s not happening. Maybe it’s like weasel words and the Avengers that come back are from an alternate reality and therefore the original versions are dead or something… But they’re coming back.

Oh wow that post about Paul being confirmed for the next movies really gave me false hope before you broke it down. And I agree completely that what he said in that interview doesn’t really say anything about his part in A4.

Awww, I’m sorry anon. I mean, we’re all hoping really hard he’s in it, so we’re leaping on the crumbs we can find. And IW has a lot of clickbait articles that are purposefully misleading hopeful fans about what happens in A4, which makes matters worse.

If it makes you feel better, this interview from Bettany has him outright stating he went back for filming in September–which was in Avengers 4 was being filmed. I actually forgot he was so direct about it. That could be reshoots for IW, or he could even by lying, but it’s pretty solid.

I think for both Lizzie and I, it’s the most exciting plotline for each
of us so far. I really loved making the first [Infinity War], we had a
ball doing it, and I’m going back in September to continue and it’s the
biggest production that I’ve been on…ever. It’s just huuuuuuuge.