Even in the worst case scenario you have the option of going out of business and filing for bankrupcy if you are incorporated in the EU and do get hit by a 20M fine. The EU can certainly try to take that amount from the company, but if it's a Ltd. or Gmbh. or equivalent its liability is limited by its shares.

Or you can incorporate outside of the EU (Guernsey or soon enough the UK perhaps?) and ignore the GDPR. At which point we'll just wait and see if the EU has any teeth outside its jurisdiction and how it will enforce this law.