The Padres might make Miller a starter in the long term though.
The pitching moves aren't that tough. Like Andy said, Rangel, Robert, Johnson. Lazar has options so they could just give him a couple of weeks away from the majors once Alvarado is back [Nola should precede him slightly] and then bring him back up in September. Walker will be in the pen at that point.
That's assuming neither Romano nor Ross are traded today, and that they wouldn't just release Ross.
Also not impossible they make another move like Banks last year, though that would almost certainly be accompanied by a reliever leaving via trade as well. I think the lesson from last year is maybe that your flawed guys in the middle/bottom of the pen are just as good as the flawed guys you try to replace them with. Though they really only traded Soto because he'd become a malcontent, not because Banks was better.