This is actually not true. I’ll explain.
The Devils could theoretically save space in case they both hit their Schedule A bonuses, which is 850K per player. These are things such as 20 goals, 60 points, Top 5 in ice time, etc. So the Devils could opt to save $1.7 million in space for that. But even still, the league allows a cushion of 7.5% above the upper limit which the team can exceed. (Similar to LTIR). Which is why a team with no players on LTIR exceeding the cap doesn’t really have to worry about the performance bonuses.
The Schedule B bonuses are the ones such as the Hart trophy, Ted Lindsay Trophy, the Calder trophy, etc. Which are very very unlikely to be hit (except for the Calder for Hughes). But even still, the bonuses paid out to Hughes, Hischier, Blackwood, Smith and Bratt shouldn’t exceed the 7.5% cushion even if the Devils were up against the $81.5 Million cap.