I see neither as real competition for a focused Bayern squad. Schalke has its obligatory midlife crisis, you said it yourself about Bremen, Arsenal isn't strong enough either, they will get kicked out of CL 'im hohen Bogen'. Well, Wolfsburg had a hard time winning against Offenbachm, but played well against Bayern, that's true. But of course, all of that is just my opinion.
They aren't bad teams in general, it's more that Bayern is really hungry this year and super focused. I'd like to see them playing Milan, Real or United. Haven't seen Juve this year so far, I guess they are pretty strong, too.