As you guys know, Joomla 4 is quite a hot topic at the moment. It is expected to be released this year, probably at the end of the summer.
Since Joomla 4 will be a major new release, there will be quite some changes in the CMS. I will not go into details about what exactly will be changed as this is not the purpose of this post, but to summarize it, there will be many back-end and front-end changes. And the biggest and most important front-end change is the switch from (the quite outdated) Bootstrap 2 to the recently released Bootstrap 4.