An EU without national vetos and with more power to sanction countries that break rule-of-law. That's two big proposals from the French/German expert report on what's needed to make EU ready to take on more members.
Obvious implications for future members UK, which would not be able to block things any more, and Ukraine, which would see its internal reforms more closely tied to EU discipline. https://www.euractiv.com/section/enlargement-neighbourhood/news/germany-france-make-eu-reform-pitch-ahead-of-enlargement-talks/