As far as I understand, the only way to upgrade Drupal (core-only) sites today is with having two sites: One is the Drupal 7 site with its own folder, and another which is a fresh Drupal 8 site in another folder; We then enable the core-based Drupal 8 migration modules in the fresh Drupal 8 site and with them Migrate-upgrade the Drupal 7 site into that fresh site.
Is there a way, maybe with Drush or with Drupal console, to actually Upgrade the existing Drupal 7 (core, or core&Ctools&Views) site directly as it is, without actually opening a fresh Drupal 8 site, besides it?
In other words, can we use the Console or Drush to update an existing Drupal 7 site directly, without any kind of migration?