Is Drupal Console aimed to replace Drush? Is Drupal Console (which is available for Drupal 8) aimed to totally or partially replace Drush?
Drupal console is a Drupal CLI tool, from the-ground-up, that leverages Symfony CLI components and modern PHP OOP design practices. Drush is a venerable Drupal CLI tool that has been around since Drupal 4.7, thus built with an older design practice. However, since Drush 9 it's been rearchitected to use the Symfony components as well.

There is overlap based on both projects being a general purpose Drupal administration CLI tool. Drush has more features, due to its age, but Drupal Console has some new features due to its more modern design. 

In a commercial software world, there would be some profit motive to merge/buy-mind-share/etc. However, in the open source world they both stand as their own independent projects, with its maintainers motivated for other reasons than to build the one true Drupal CLI tool to bind them all (tm).

It might help to read Ten things you need to know about Drupal Console coming from Ray Saltini of FFW (the company supporting the lead developer Jesus Olivas of Drupal Console), &amp; Drush and the Drupal Console with Drupal 8 from Greg Anderson (one of the maintainers of Drush).

To explicitly answer the question, maybe. If you're wondering which should I use?, the answer is maybe both for the time being. Perhaps Drupal Console will eclipse Drush, but right now both have useful feature sets for administering your Drupal site.