Messi and Ronaldo are still icons of world football. Although now their performance is declining in each of the teams they defend. But his appearance is still awaited by most football lovers. Moreover, this is a World Cup where these two players have never lifted the trophy of the biggest party in football. Not only that, disputes between two fans still occur, especially on social media, both fans are still comparing who is better between the two even though there are now many talented young players born.
Even if these two have retired, that won't erase the fact that they are once an icon in the football industry, the same as with Muhammad Ali in boxing. Even if he isn't active in that said sport anymore his names are still everywhere and being talked about up until now. It is normal for their performance to decline over the years because they are only a human and they grow old too where their ability can deteriorate.
The time will come that they will be replaced by a much younger and more skilled player although it is not easy for them to be in the level of those legends that we know. They need to practice and have more experience.