For next season, even though they are quite brilliant in the playoffs this time, that is not a guarantee either. At the moment Stuttgart will only be a club that is at the bottom of the table but they are aware of that but of course with them continuing to be in the bundesliga it is already very good for them.
I actually saw Darmstadt condition from the previous season but indeed towards the end of the season they always stumbled and this season they were finally able to penetrate the highest caste after waiting for a long time to return to this caste.
Indeed, Stuttgart will certainly not be able to meet our expectations to be able to perform better next season, even for mid-table positions, they will definitely have difficulties. I think it is true that they are still the bottom team in the standings, but at least they have to change their game a little so they can finish in a better position. Talking about Damstadt I haven't heard of this team before and if they have an unusual process to the bundesliga, they might be a pretty tough challenger next season, only if Damstadt can be consistent in their matches.
They have to try again now because it's a good chance to try again next season but if they still can't be there then maybe something like Hertha this season will still happen for Stuttgart.
As for Darmstadt, actually in the last 2 seasons I have always taken the time to watch Bundesliga 2 and indeed their performance is not bad even with the fairly tight level of competition there. but their problem last season was they failed to be consistent actually this season also they still have the same problem it's just that this season is a little bit better.