Barring any possible delays, The Division 2 should land before the end of March 2019, but it will not come before October 2018. This basically leaves a six month window during Q4 2018 and Q1 2019 for Ubisoft's next bullet sponge festival.
Ubisoft have on their upcoming AAA titles earlier, with four AAA titles set for release between April 2018 and April 2019. Three titles have been confirmed so far - The Crew 2, Skull & Bones and The Division 2. The fourth title is a mystery so far since there is no indication on how many years are there before Beyond Good & Evil 2 comes. That said, we're rooting for a new Splinter Cell entry, which is quite possible since the evidence of a Splinter Cell has slowly been over the last few months.
But I digress, back to The Division 2 talk. So, The Division 2 will be coming before April 2019, but how come it's not going to pop up in the next few months? Well for one, there will be "Shields" achievement system that will allow The Division players to farm up rewards for The Division 2. These Shields will start popping up in June 2018 and will go on for at least four months, with the last confirmed continuation of the feature being in September 2018.
It wouldn't make much sense to release The Division 2 before the reward system for it could be completed in The Divison, so there are only October, November and December left as possible 2018 release months for the game. Other than Shields, July, August and September will be pretty uneventful for The Division which pretty much spells out that all hands are on The Division 2's deck.
Meanwhile, Ubisoft have confirmed that The Division 2 will be revealed on E3 2018, which is less than a month away. Now may be a good time to start asking ourselves if they will reveal more about the game than we thought. Like a proper release date, for example.