A feature for upgrading already installed installations to a newer version would be very neat. I will always install the latest patch for maximum security and less bugs, but it is quite tedious to install a completely installation every single time there is released a new patch, so a feature where you can upgrade your installation to the latest available patch would be nice.
It is good that each major version is its own installation, but a feature where you can upgrade a minor release to a newer minor release would be very useful.
Anyway, Unity Hub is looking good so far, and I’m looking forward to more improvements.