Microsoft has confirmed that it is holding off implementing extensions for the new browser until next year:
We’re committed to providing customers with a personalized web experience, which is why bringing extensions to Microsoft Edge continues to be a high priority. We’re actively working to develop a secure extension model to make the safest and most reliable browser for our customers, and look forward to sharing more in a future Windows 10 update in 2016.
Edge is designed as a swift consumer browser that is destined to replace the much-maligned Internet Explorer for most people. A new engine, coupled with features like WebNotes that let you draw on a Web page, are useful additions.
Not having popular add-ons may slow adoption of Edge, especially for users who depend on certain extensions for their professional work. The fact that the company has not given a target date for adding them, is a bit discouraging. Lack of extension support is seen as one of the browsers’ greatest weaknesses, compared with Chrome and Firefox.
➤ Extensions For Edge Delayed Until 2016 [Thurrott]