According to Jacob Wolf, sources close to ESPN state that Blizzard will unveil the six founding members of Overwatch League on Wednesday.

This follows the creation of the official Overwatch League Twitter. 

It was only a few days ago when the story broke that the Mets, the Patriots, Immortals, and NRG Esports will be four of those spots. We'll have to wait and see, but Q3 was the proposed start date for the Overwatch League and we only have a few months left. So Blizzard better kick it into high gear if they want to meet the aforementioned timeline.

Granted, making this announcement is a great first step.