I've read many times about players who come back after an absence (a long one) and they usually have a big debt.
I'm sure iGP games doesn't like to lose players who cannot wait weeks or months to recover a 100+ mln debt.
My idea is a bankrupt button which simulates a failure available during the season break and if balance is below -50 mln.
When clicked: the balance is 0, tokens are 0, drivers and staff are lost, player's level is decreased by 5 (like every headquarter building) and technologies restart from level 1.
This way players are more engaged and don't quit the game.