Frankfurt would be happy if the current ranking is the final ranking of the season. They have unprecedented successes there for a club that has not achieved much in recent years. And financially they will also be well off. You also have a lot of television money in Germany, so it is not only attractive from a sporting point of view to finish high. The higher you finish, the more interest you will have in the television money that will then be distributed.
As far as I know club income from TV rights is significant only in the Premier League. Therefore, Frankfurt would be happy to remain in their current position only because 4th place provides a direct ticket to the Champions League where the club's income is significant. But it will be difficult for them to hold this position as Dortmund are behind, plus Union Berlin will probably get back in business and play well again.
Yes it will be tough to stay in that position, from the second throught the sixth i think we will see a lot of changes there is as much chance seeing frankfurt second as seeing them sixth, this competition will make the bundesliga interesting even if there is no competition for the first spot.