Will CiviCRM work with Backdrop?
CiviCRM is very flexible. The current (4.6) core integrates simultaneously with Drupal 6 &amp; 7, Wordpress 4.x, and Joomla 2.5x &amp; 3.x. With a few tweaks it can even work as a standalone app without any CMS.
Could it work with Backdrop? Undoubtedly yes, and it might even be as easy as you suggest. Will it be released with a Backdrop version? I think that's up to everyone. If this is a priority for the community, then it will be a priority for the community.
UPDATE: Take note of CRM17711 on Jira for this topic (&quot;Add Support for Backdrop&quot;)
UPDATE2: Backdrop support is officially in place, with a stable download and its own installation page on the Wiki.

The Backdrop team has been working together with Tim Otten to provide support for Backdrop CMS within CiviCRM.
As you may know, Backdrop is a fork of Drupal that maintains most of the APIs of Drupal 7 while providing new functionality like configuration management, more powerful layouts, and built-in Views in core. Backdrop is trying to bring down the cost of ownership by shifting Drupal's backwards-compatibility approach. Drupal basically commits itself to drastic changes every few years, while Backdrop is committing to a more WordPress-like approach of minimized API changes while providing new functionality.
Backdrop's primary audience is budget-restrained sites; putting us in the SMB, education, and non-profit space. Basically, the same we hope as CiviCRM. Supporting Backdrop would be a great way to bolster both projects.
As Backdrop is so similar to Drupal 7, we expect the porting to go fairly quickly, though it may result in a lot of similar code to the existing Drupal integration. Considering Backdrop (or Drupal) may diverge further in the future, it's likely that adding Backdrop as a new top-level CMS (e.g. the same as WordPress or Joomla) would be a better long-term approach for maintenance.