Actually I think the current impact of daytrading is overrated. Effective Daytrading is a thing of the past, as of late it´s very hard to get ANY money out of pure transfer moves.
I think "tanking" (which is btw legal) is a more key issue - it has to be (a) less economically profitable, (b) less intriguing in case of draft picks and (c) severely punished when it happens in combination with walkovers.
Also, a "luxury tax" could be interesting: once your bank account holds more than 10 times the average salaries of your season, you have to pay 0,5 % "taxes", more than 20 times 1 %, more than 25 times 2 %.
It would become alot harder to play the game the Dagobert Duck way then.
Zwei Dinge sind unendlich, die Dummheit und das All...