The text says "several", but it mentions only four components (gdebi, apturl, aptdaemon and mintcommon-aptdaemon) merged into two (captain, aptkit). It doesn't look like much, and typically the Mint project is responsible to not claim to maintain more than it can maintain¹.

In special, I remember gdebi being broken for quite a while², so this hints that Mint's goal is to get properly maintained replacements.

1. As shown by Cinnamon. I personally don't like it, but it is well maintained, even being a huge project.
2. If I recall correctly, the issue was with the associated gdebi-gtk frontend; you'd open a package with it, then click "install", then the program exits because it's looking for sudo instead of pkexec. I'm almost certain that it was fixed by now, but it does show general lack of maintainance.