With many of the touring industry’s biggest names rapidly reaching retirement age — some 15 of the top 25 acts since 1990 include at least one musician over 60 — the question of succession is taking on increasing urgency. But a changing of the guard is coming into focus, with Rihanna, Taylor Swift, One Direction, Jason Aldean, Katy Perry, Lady Gaga, Luke Bryan, Miley Cyrus, and Bruno Mars among the top 25 tours of 2014-15.

Moving up to the arena/amphitheater level (venues with capacities topping 10,000) is a milestone career move, and in most cases a risky proposition. “Beyond the hits, you’ve got to be an entertainer,” says Live Nation vp Brad Wavra, who has seen many such jumps as producer of tours by Backstreet Boys, ‘N Sync, Jonas Brothers and the upcoming 5 Seconds of Summer tour. “That’s the subjective part, and the fans get to vote.” Below are five acts making the leap to arena/amphitheater tours — or attempting to — in 2015.

Ariana Grande

With a higher average ticket price than sheds — and all reserved seating in most cases — arenas can be a tough sell for ascending artists. But Ariana Grande is proving she is more than up to the challenge. Still, when her team first committed to an arena trek, it was “a little cautious at the beginning,” says Wavra, so they had the seating capacities in the buildings reduced. But “as sales kept evolving, we peeled back the drapes, pushed the stage back, and now she’s full-blown arena.” Grande is averaging more than $560,000 per night at the box office on her current tour (which runs through mid-April before heading to Europe), with attendance of nearly 12,000 per show, according to Billboard Boxscore.

5 Seconds Of Summer

The Aussie boy band blew up so big and so quickly as the support act on One Direction’s 2014 North American stadium tour that some feared the group’s career would be over before it could headline its own outing. That didn’t happen: 5SOS began topping big bills in the fall — including a two-night stand at the Los Angeles Forum that grossed $1.2 million, with attendance of 25,170 — and are off to a “good start,” says Wavra, for a run that begins July 17 in Las Vegas.

Florida Georgia Line

The duo was third on a three-act Luke Bryan tour in 2013 and second on a 2014 Aldean tour; now it’s another graduate of country’s tried-and-true “first of three, second of three, headline” artist-development model. Throughout their support touring, FGL have tested the waters with headlining dates, topped by a barnstorming run through seven minor league ballparks last year that grossed $3.2 million from 82,006 attendance, according to Boxscore.

Now FGL are ready for prime time. “It’s about strategic touring, career building with hard tickets, and gradually bumping the price up just to see where we sit,” says FGL agent Kevin Neal at William Morris Endeavor Entertainment.

FGL’s 2015 trek began Jan. 15 in Toledo, Ohio, and runs through Oct. 17 — the 14 shows reported so far have grossed $17.3 million, on ticket sales of 136,533 — with 16,000 sold already for its May 9 shed tour launch in Columbia, Md.

J. Cole

Hip-hop has enjoyed a renaissance in the touring world during the past few years, and J. Cole‘s jump to arenas — granted, with support from Big Sean, YG and Jeremih — has been an unqualified success, with major-market plays like the 18,000-capacity Staples Center in L.A. and New York’s Madison Square Garden selling out in less than an hour. Cole’s tour in support of 2014 Forest Hills Drive is a well-conceived outing broken down into Act I–The Hometown Edition (underplays in smaller rooms and markets), Act II–The Journey (a run through the U.K. and Europe, including a sellout at London’s O2), and Act III–Hollywood (coast-to-coast arenas and amphitheaters, culminating with a hometown show in Fayetteville, N.C., on Aug. 29. Robert Gibbs, Cole’s agent at ICM, says the rapper “invests a lot of time in [his touring career], from the venues to ticket prices.”

Iggy Azalea

Her megahit “Fancy” turned the Aussie MC into a household name in 2014, but those factors don’t always translate into arena-level ticket sales. A month before Azalea’s scheduled April 14 Great Escape Tour launch, the jaunt was postponed until September due to production delays. While such delays are not unheard-of in the frenetic world of touring, tours with robust ticket sales nearly always find a way to work around them. One industry observer characterized the tour as “a complete crash and burn,” noting Azalea’s lack of multiple hits and a touring history mostly comprising festival appearances, radio shows and several previously booked venues. “There was a big guarantee, a big ticket price and no fan base,” the observer said. “They brought it down because it was a financial disaster.” Promoter AEG Live did not respond to requests for comment. [Billboard]