Shortly after the news broke about WrestleMania taking place in the WWE Performance Center, the @fightoracle Twitter account (who has shared a lot of correct rumours in the past, including Edge's return and CM Punk's deal with FOX) claims that WWE could hold the Showcase of the Immortals in New York City's Madison Square Garden on June 7th.
Part of the reason for this is the fact WWE's insurance policy which covers any potential losses with WrestleMania states that they have a duty to mitigate damages. Using the WWE Performance Center achieves that, but the belief is that the city of Orlando won't allow it to take place there (Las Vegas has banned all combat sports, for example), so WWE can prove to their insurer that they did their best to host WrestleMania.
When that happens, the company can move the Show of Shows to Madison Square Garden, and deliver a version of the PPV which actually lives us to expectations...one in an empty warehouse definitely will not.
Ultimately, it's hard to say what will happen because we don't know how long this pandemic will last for. Still, this is a very interesting rumour, and one which could shed some light on WWE's plans moving forward.