I work for the IT department at the University of Wisconsin Madison. The University has adopted a new accessibility policy based on WCAG 2.1 AA which has brought greater attention to accessibility barriers imposed by WordPress plugins.
WP DataTables imposes several barriers, including but not limited to:

Lack of visible focus indicators when navigating via keyboard.

Ideally, tabbing through these elements should show a clear focus indicator such as a CSS outline:

* Links within tables
* Pagination links beneath tables

Placeholder text has insufficient contrast to meet WCAG requirements.

Table filter lacks screen reader support:

* There is no indication that entering text in the filter field filters the column, nor any status updates when the filter is applied. Such state changes must be announced via a screen reader to meet WCAG requirements.

Please remediate these barriers and any others not mentioned that prevent the plugin from meeting WCAG requirements in an upcoming release of the wpDataTables plugin. Please note that the University's accessibility policy requires us to procure accessible technology tools. If WP DataTables is not made WCAG compliant, we may not be able to continue renewing our license.

Milos,

There's no need to become 100% WCAG compliant at once. A good start would be to fix problems introduced by not following best practices for accessibility. The WPDataTables stylesheet explicitly removes visible focus indicators from the pagination buttons, for example. This is bad practice and is easily fixed. 

If you aren't doing so already, I suggest you review the barriers reported here and in other tickets, identify those that have easy fixes and make some quick wins. 

After that, prioritize those that remain and address them incrementally. At your usual rate of 1-2 update releases a month, it wouldn't take very long to address them.