According to a report from Barnburner, WWE is apparently planning to hold “more than one WrestleMania event per year by 2020.” The site says the secondary WrestleMania event would follow a similar format to that of the Greatest Royal Rumble and Super Show-Down events, where they would be heavily promoted international events.
WWE wants to have one in April and the second one in October. As of now, Saudi Arabia, London, and Australia are possible hosts for that second show.
Obviously, it’s highly unlikely they would use the “WrestleMania” name. They would come up with names like the Greatest Royal Rumble and Super Show-Down but they would be on the same level as WrestleMania in regards to stadiums, attendance and production.