The secrecy around these Star Wars movies may seem ridiculous but of course, it’s a necessary evil if you want to avoid plot detail leaks/spoilers.
With Rogue One: A Star Wars Story, Disney and Lucasfilm have proven that there’s an audience for Star Wars films that go back in time and explore events that took place between the prequel movie trilogy and Episode IV – A New Hope.
As we already knew from The Empire Strikes Back, Lando Calrissian is a big part of Han Solo’s pre-New Hope existence.
At some point in the near future, Glover will show up for work to play Lando and he will at least have read his own scenes.