Unlikely that this kind of growth suddenly happens. Growth of +\- 20% can usually be handled (eg booking a larger room for the lectures). So studies can usually grow their teaching base as needed.

Exceptions happen: eg the popularity of CSI lead to a huge boom in people wanting to study forensic sciences. IIRC they were allowed to limit the seats for those studies back in the day.

Similarly, dentistry and doctors have a fixed amount of seats. They have a lottery that is biased based on your high school grades.

Overall I think this system has the better outcomes ‘on average’, but that the true top students are not challenged as much as they would be in a more selective system such as the US/UK

They would probably have their government fund building more univiersities and training / encouraging more people to become professors?