In 2019, the Ninjago sets are now named as LEGO Ninjago Legacy which you'll find some of the sets are pretty much similar to the old sets with mixtures of new elements. I believe this move is to capture more new Ninjago player in the coming years.
Anyway, there are total 14 new Ninjago sets to be released in January 2019. Let's have a looks at each of them.
LEGO 70659 Spinjitzu Kai - Comes with 97pcs
LEGO 70660 Spinjitzu Jay
LEGO 70661 Spinjitzu Zane -
LEGO 70662 Spinjitzu Cole - Comes with 117pcs
LEGO 70663 Spinjitzu Nya & Wu - Comes with 227pcs
LEGO 70664 Spinjitzu Lloyd vs. Garmadon - Comes with 208pcs
LEGO 70665 The Samurai Mech - Comes with 154pcs
LEGO 70666 The Golden Dragon - Comes with 171pcs
LEGO 70667 Kai's Blade Cycle & Zane's Snowmobile - Comes with 376pcs
LEGO 70668 Jay's Storm Fighter - Comes with 490pcs
LEGO 70669 Cole's Earth Driller - Comes with 857pcs
LEGO 70670 Monastery of Spinjitzu - Comes with 1070pcs
LEGO 70679 The Ultra Dragon - Comes with 951pcs
LEGO 70680 Monastery Training - Comes with 122pcs