Source: Josh Alper, NBC Sports Pro Football Talk 
We’re starting to get some idea of what Blackmon will do between now and then. Adam Schefter of ESPN reports that Blackmon will enter a rehab facility in response to the suspension.
Jaguars announced WR Justin Blackmon suspended indefinitely.
— Adam Schefter (@AdamSchefter) November 1, 2013 
While it’s not clear what Blackmon did to trigger the new suspension, heading to rehab is a way to signify a serious intent to change one’s ways before it becomes time to ask back into the league. Blackmon will also be subject to unnanounced testing throughout his suspension and a rehab facility should be a pretty good place to avoid the kind of behavior that lands you on the suspended list.