The Star Wars film world is still reeling from the announcement today that writing/directing team of Phil Lord and Chris Miller who were doing the Han Solo solo film had parted ways with the galactic giant. Rumors abound, of course, as they would in such a situation.
Popular theories that don't seem unlikely include things like going over budget, not being able to stick to studio appointed time tables, and the most likely (being cited as the reason for the break) creative differences between Lucasfilm President Kathy Kennedy and the pair.
Another incredibly possible theory is Miller and Lord's work on the DCEU solo Flash film. No really, they wrote the script for Warner Brothers (announced back in May) and were at the middle point on the short list of directors the studio was looking at to head the film. They originally turned down the directors chairs because it "wouldn't fit in their schedule". Sure seems like that point is moot now.
Variety doesn't name names, but has some "inside source" commentary that make the Kennedy angle the most likely of reasons. They also outright say the pair did not leave the project by their choice, but were actually fired, an important distinction in the rumor fuel.
The yet unnamed Han Solo solo film has been in filming since February, and still has a release date of May 25th 2018. We'll keep you appraised of any more developments that come down the pipeline, and probably toss a short list of possible directorial replacements your way, too.