SSH already has host and key management via the user's config file.

I somewhat understand the desire for an SSH client that behaves like the Docker shell, but it needs some features that actually set it apart.

How about putting different hosts into groups, and then running a command on the group so that every machine in the group runs the same command?

How about managing both hosts and users so that I can easily log into a system as different users for different purposes?

How about adding some security features to make key management more secure than the standard "everything in the .ssh directory" strategy?

Maybe add some SCP/SFTP features so that moving files from host to host is easier. Maybe even have a package you can install on remote hosts so that they can transfer files directly between each other when asked to from an outside terminal.