Any useful master plan is adaptable. The MCU master plan changed when they struck a deal to let them use Spider-Man. It changed when they broke with Ike Perlmutter and were free of his insistence on an Inhumans movie and his resistance to female and minority leads. Before that, it changed when they decided not to do a Hulk sequel and replaced their tentative Runaways movie with The Avengers (good choice).
Plus, the upside to the Covid situation shutting down/slowing production means that they now have extra time to work on all the new stuff they got from reacquiring the X-Men characters from Fox.