-1 to the general idea of removing multisite completely.
This will be a big ...

-1 to the general idea of removing multisite completely.

This will be a big issue for many current setups which use multisites, there will be challenges in moving to new Drupal versions for these setups and also possibly a rework on hosting and devops front.

I agree that multisite setups have their own challenges, especially ones with shared database. But most people have found a way to get past them and make it work.

It would be preferred to have better documentation on a multisite setup and various configurations, so that people know the advantages and disadvantages beforehand.