As of DreamHack Atlanta, it has been announced that Microsoft Stores in the U.S., Puerto Rico, Canada, and even Australia will be hosting monthly tournaments for local players to meet and compete. Here is the trailer where you can see Kenny the Spartacat talk about prizes and what these tournaments bring to the Halo Community:
August 6 - FFA Tournament
September 3 - Doubles Tournament
October 8 - 4v4 Tournament (HCS Settings)
Areas supporting the events:
If you love playing Halo 5 still then it is encouraged to go to these. You never know who you'll meet or what you'll win!
Source: Halo Waypoint