According to Ubisoft, it plans to support the game for 10 years, though whether or not the company was being hyperbolic is unclear. Should it stand by this statement, Siege support could be expected as far into the future as 2025.
One reason the company might be avoiding a sequel could be the game's continuous growth since its release in 2015. During the Invitational, Ubisoft said the game had reached 27 million total players, up two million from December 2017.
The company also revealed some new features and changes to the game coming in the future. The changes, as detailed by Reddit user URZ_, are as follows:
8 new operators are coming in Year 3. Goal is still hitting a 100 operators eventually.
Changes coming to the standard edition. You will now start with all 20 legacy (original) operators unlocked.
In the future all weapon attachments will be free and unlocked from the go.
The problem child that is starter edition will go from 4 free operators to 6.
They are adding new Data-centers in South Africa and South Europe.
Pick and Ban is coming for operators in Pro-league. Each side gets to ban 1 attacker and 1 defender for the whole map.
Pro-league will be 1 team attacking 5 times followed by the other team attacking 5 times.
They will be working hard on improving the Pro-league in general. They are first of all reworking the observation tool.
Some maps will be renovated and rebalanced. Bomb-mode will be the focus for map design.
The map "Yacht" is coming back to casual.
The Map "Hereford" will be the first map to be reworked.
Every season (at least that is the goal. Changes will ship when ready) a map will receive a buff. Small changes that should help improve the meta on the map, mostly through improving specific objectives to make more bomb-sights viable.
First map to receive a buff is "Clubhouse". Bar-room and Top floor will both be buffed. They are aiming for season 2 as the goal for completion.
Esports is there to stay.
Lan-competitions will happen. Dreamhack got name dropped but didn't catch the context.
Rainbow Six Siege was originally released in December 2015.