Howard, who stepped in to helm the project following the firing of original directors Phil Lord and Chris Miller, said in May 2018 any sequel or sequels would be determined by fan response and their subsequent turnout at the box office.
"I think the fans are going to define all of that," Howard told Fandango.
"I mean I think that Lucasfilm and Disney in casting actors, and particularly younger actors, want to see what happens and build upon that. Certainly, they want the commitment from the young actors, but there are no concrete plans. I think there's been a lot of creative energy and now marketing energy going behind this movie."
Asked about the anthology series centering around one-off adventures, Howard said, "I think these are exactly what they're meant to be, or what they're designed to be."
"They're single movies exploring the galaxy; but of course, as a company, I think they're going to be very interested to see how people respond to it and take it from there," he continued. "This whole thing is kind of a cool, ambitious exploration of what the galaxy and the Star Wars sensibility can continue to mean to fans."
Howard's comments came before Solo grossed just $392 million worldwide, making it the lowest performing live-action Star Wars movie.
Walt Disney Studios chief Alan Horn previously told The Hollywood Reporter the prequel, starring Alden Ehrenreich as the younger Han Solo, "didn't resonate as much as we'd hoped it would."
Whether or not Solo sees a continuation — either on the big screen or on Disney+, the coming streaming service that will host the first-ever live-action Star Wars television series The Mandalorian — Howard believes a potential followup could explore the five major crime Syndicates.
"Potentially one would think it might be kind of interesting to see what a war amongst the Syndicates looks like," he told Empire Magazine.
"There's nothing concrete there, but that's interesting territory. In what movie and through which character's perspective that might emerge... I think everybody feels like that's rich territory to explore in the movie universe."