The cap could very well stay flat for the 2020-21 season. It's just another side-effect of suspending the 2019-20 season due to the COVID-19 pandemic. That puts teams, like the New York Islanders, who are close to the cap ceiling, in a tough position.
Going into 2020-21, the Islanders have $71.38 million committed to players. With a flat cap ceiling of $81.5 million, that leaves the Isles with $10.12 million in cap space. That's not going to be enough room to sign Mathew Barzal, Ryan Pulock, and Devon Toews to extensions.