Disney Parks & Resorts has announced that Live Music will be featured at Disneyland's Tomorrowland Terrace Stage for a limited engagement:

Quote Originally Posted by Disney Parks & Resorts
Live music is returning to the stage at Tomorrowland Terrace. Guest favorites such as 80z All Stars, Scot Bruce, Suburban Legends and more will be performing on weekends, Friday through Sunday, beginning August 6 for a limited time. Different bands will appear from day to day. Be sure to check the entertainment schedule before your visit.
As noted, the end date for this "limited time" offering was not announced.