Fox has decided to move some of their properties to different release dates.
Black Panther has the most pre-sale tickets.
https://www.polygon.com/2018/1/10/16873804/black-panther-ticket-sale-record-marvel
A Standalone ‘Black Widow’ movie is in the works. The writer Jac Schaeffer has been hired to pen a script for the movie.
http://variety.com/2018/film/news/marvel-black-widow-jac-schaeffer-screenwriter-1202643908/