We already know that Chewbacca
There’s currently no word on who is being considered for the role, but both The Empire Strikes Back and Return of the Jedi teased some history between these two, so there could be a lot of material to explore. Throw in the fact that it was recently reported that we could see an entire trilogy of movies revolving around Han Solo, and chances are that we’ll be spending a fair bit of time with new Lando. Who knows, he may very well get his own movie!
For now though, all we know is that the code name being used in casting circles for the role is “Chance”, a moniker which makes sense given his history with gambling. With a release date of May 25th, 2018, Lord and Miller have plenty of time to find the perfect actor for the young Lando anyway, so stay tuned for further updates on this one over the coming months.