UPDATE Pokemon Go New Adventure Sync Hatchathon Event Announced January 2-January 15

Trainers, a new Pokemon Go Adventure Sync
The notification:
Attention trainers!
New Hatchathon Event coming soon, with Double Candy and Stardust for Hatching Eggs, and an increased chance on getting 5km and 10km eggs.
There is also an official newsletter with the following info:
Welcome a brand-new year with the Adventure Sync Hatchathon! To celebrate new beginnings, Trainers will enjoy bonuses for hatching Eggs from January 2 at 1:00 PM PST to January 15 at 1:00 PM PST. Make sure your shoes are tightly laced for a long journey, as you’re more likely to receive 5KM and 10KM Eggs from PokeStops and Gyms. Don’t forget to activate Adventure Sync to make your steps count toward hatching Eggs…
For your reference, here is the list of all 2km, 5km, 7km and 10km Eggs!
Good luck and hatch ’em all!