The schedule will probably change, but it will almost certainly be gradual. There are still a lot of Cubs fans who believe lights are the tools of The Devil.
Cubs owner Tom Ricketts already said once the Cubs complete most the renovations to Wrigley Field, the team wants to play a lot more night games there—probably half their home schedule. If they can pull that off, the Cubs will be far more successful in the playoffs, since the players will be more used to be night playing schedule given that most League Championship Series games and all World Series games will be played at night.