Prior to the New Year, the WWE was planning on having their first Wrestlemania main event featuring female stars. The plan was for Ronda Rousey to face Becky Lynch, but this match may be changed according to a news from Dave Meltzer at The Wrestling Observer
Meltzer noted that changes have been made to the Royal Rumble card, and the original plan was to have Ronda Rousey vs. Charlotte. Rousey is now scheduled to face Sasha Banks at the event, and this could lead to Charlotte being added to the Becky Lynch vs. Rousey match at Wrestlemania.
It was noted that this is not official, but at this point in time it is under consideration. This possible change is what led to WWE replacing Charlotte with Banks for the Royal Rumble.
The WWE does have Elimination Chamber and Fastlane prior to Wrestlemania, so they could insert Charlotte into a match with Rousey at one of those events, and keep Lynch vs. Rousey for Mania.