Apparently, proposals are floating around EU parliament about setting rules for minimum free carry-on sizes. limits, even for budget airlines. (Caviats: 1- EU parliament isn't the fastest-moving legislative body. 2-Costs may just shift into the base tickets.)
I saw/read the story on El Mundo, so found this travel-blog link to share in English: https://www.offthebeatenpoints.com/the-eu-will-vote-in-october-whether-to-ban-fees-for-carry-on-bags/