No real reason why it couldn't happen. As the headlining inductee, or inductees as it were, the nWo would help sell a lot of tickets to the HOF ceremony. That's first and foremost Vince's priority because the HOF ceremony is, for all intents and purposes, a wrestling show that simply doesn't feature any wrestling matches but relies on nostalgia to make money; some knock the WWE HOF but it's probably the only pro wrestling HOF that the vast majority of fans give a damn about whatsoever and while I, like just about everyone at one point or another, have no shortage of criticisms for Vince McMahon, I take my hat off to him as he figured out another way to milk even more money from fans during WrestleMania weekend.
If, for whatever reason, they're not able to get Hogan, Hall, Nash and Bischoff all together for the induction in 2019, then I'd just hold off until they can because even though damn near every relevant, or semi-relevant, member of the WCW roster was part of the group at some point, those four will always be the original and core group in my eyes.