4: An NXT Invasion
This has been something fans have been hoping for, for years, and 2019 could finally be the year of the NXT Invasion.
Arguably the hottest thing in WWE right now, NXT has been a tour-de-force since being revamped in 2012, with the recent NXT UK brand only adding to the developmental ground's success.
As for who would be part of said invasion, the Undisputed Era seem likely choices, as they are all expected the be joining the main roster in 2019.
Whilst NXT has been a haven for so many stars, so many more have fallen by the wayside when they join the main roster, such as Tyler Breeze, Apollo Crews and Fandango.
What better way could the quartet of Cole, Strong, O'Reilly and Fish guarantee success than sticking it to the main roster on their very first night?