Ah, you're basing your points on the notion that they'd play a back-4 setup. From what I've seen, I don't think they're defensively good enough to play with a back 4 yet.
Aside from Haaland they have every position covered by two dedicated first team players, even more if you consider that some of them can play more than one position. By Dortmund's standards that's a deep squad.
If that's their direction going forward, though, whilst they would have more than 1 option per position, I'm not so sure if the backup options would be good enough. I'm not confident about Piszczek as a CB in a back 4. Morey hasn't shown much as of yet whenever he came on as a sub last season.
They may have attacking depth, which I already acknowledged in my previous post, but they need better-quality defensive depth.