>>41592593It is possible, yes. EVERYTHING can be replaced. Audio, signs, arena layout, stage, video files. It takes a lot of work since it requires a minor bit of insight with hex editing but it's becoming easier than ever.
Here is an example of a recently modified arena from the community. Yes, this is the Marvel Avengers base. By all accounts, you could likely take one of the Niji VR maps and dump it atop