I think it will be open ended. It’s better to be able to continue the adventures of young Solo. The actors are young, the characters are loved by the public, why not a series of film ?
Twenty years from now, Solo will have been retitled: Solo: Episode IV, and they’ll be working on the sequel Solo Trilogy.
Solo: Episode IV - A New Bounty: A Original Star Wars Story From The First 15 Movie Running Stories Saga