Honestly those suggestions about crippling yourself to cripple the rival aren't at all rational or realistic. Not in Germany, not anywhere. The first thing any club should care about is their own well-being. With stuff like this you damage yourself way more, and if everyone does that, you just damage the entire league.
Actually the most interesting and out-of-the-box thinking point I ever heard from someone who criticised the business of BuLi clubs was about the approach of singing young players. I had a friend from Sweden who told me that he doesn't think that's at all profitable and they will leave anyway when they are good.. He said he would rather pay the same fee for a 26+ player because that player will likely be better than an 18player for the same price, plus top clubs won't show interest in him when he peaks because he's already in an unattractive age. That means that some smaller clubs can keep their squads and stars together. Not saying I'd prefer that to the approach of signing talents (I mean they are just exciting), but I think this is actually perfectly viable tactic for smaller clubs that opposes this obsession with finding the next young Messi.
I feel you would not cripple yourself in sucha terrible way that its impossible to overcome.
Say a team takes this approach now. Talents wont be so eager to join but those who do know the consequences. You can target foreign talent and 26 year olds like you said for the short term.
Then when you have solidified your position/reputation you can target german talent more.
Problem with signing 26 year olds is that for them to join the likes of schalke they are top club rejects or relative mediocre players who you cant profit on. You can still sell the likes of dembele to the barca/Real of the world rather than say Babel and make no profit on the more unwanted experience player.
Whats also possible (to suggest a less extreme approach) is to put in Bayern clauses where they basically pay twice as much than normal clubs but yiu still keep the consequences for not renewing.
So say max meyer can join Real for 60m, Bayern pay 100+ if they really value the player they will cough up the money. This of course would never happen to Bayern being cheap but atleast you offer the illusion of a possibility to join your favourite team.
I prefer the more extreme strategy but there are more possibilities rather than just accept this situation.