Hm, I can still see some use for it, but not too much of a use like its broken or anything though.
I find it sad that Samael won't be coming out anytime soon(not that I can actually secure a spot for her, i'd have a pretty difficult time in deciding who i want to remove from my own team but she's still pretty good to have)
I don't think they'll do that. She's already good as she is (I also don't recall any dark SSR hime right now that has a C frame atk debuff)
If they did want to change it, they would've already when they did the upgrades to Amon U
I only have a few teams that actually use joan as main soul, so I can't really tell for myself. Maybe I'll test it in the future...
Heck even sniper shot sometimes trolls me in some quests
And wait a sec, why would u want to run ambush?
I know satan's A frame is weaker, but lets say you have AW satan, dark amat and upgraded Amon U, you'd already reach the def debuff cap. I'd rather bring something else. maybe something like Provisional forest if you can run a burst build or even desertion is a better option
And even then, if you managed to get thanatos now, and have the same setup (except thanatos in amon U's spot) you'd still be reaching that def debuff cap..