What happens when bro-country grows up and settles down? Fans of Florida Georgia Line will find out when the chart-busting duo releases their fourth album in early 2019. Tyler Hubbard and Brian Kelley have already teased where that sound might be heading with “Simple,” the lead single from the forthcoming song set that finds the duo favoring a banjo-flavored, back-to-basics approach that’s more Mumford & Sons and Edward Sharpe than Jason Aldean and Luke Bryan. It became Florida Georgia Line’s 16th visit to the Top 10 Billboard Hot Country Songs, coming in the wake of their collaboration with Bebe Rexha on her No. 2 pop hit “Meant to Be.”

“Meant to Be” made Florida Georgia Line ubiquitous on the airwaves and holds the record for the longest reign as the No. 1 Hot Country Song with an amazing 46 weeks at the top slot and counting as of mid-November. It’s only been six years since Hubbard and Kelley helped define the bro-country sub-genre with the release of “Cruise,” leading to an entire movement of songs about appreciating bikini tops, tailgates and tanned legs while “sippin’ on Southern … in the sweet heart of the summer.”

While the hip-hop-influenced sub-genre weathered criticism from some factions within the country music establishment, it flourished among its young listeners. Its connection to hip-hop may be more than just stylistically cosmetic: As trap music helps provide an escape via hip-hop in a world increasingly made confusing and chaotic by forces beyond control of the youth demographic, bro-country similarly provides a no-worries reprieve from stress for its adherents. For a few minutes, as FGL sings on “This Is How We Roll,” life is nothing but good times and girls. “This is how we roll / This is how we do / When the world turns ugly / I just turn and look at you.”

“Simple,” with its whistled hook, comes from a place of marriage and settling down, but Hubbard and Kelley reassure their party people on the second song to be teased from the album, “Colorado,” that growing up can be balanced with good times. The third, “Talk You Out of It,” may confuse the establishment further by name checking Luther Vandross in what is essentially a slow jam about skipping the party and slipping between the sheets. Fourth teaser extolls the virtues of “Sittin’ Pretty” with a significant other: “We got all damn day to do it our way / Like an old tire swing in the shade … I’m just fine long as I’m sittin’ next to you.”

The rest of Florida Georgia Line’s upcoming album remains a mystery until next year, including what sort of hand longtime producer Joey Moi has in the new material. “Simple,” “Colorado” and “Talk You Out of It” have been part of the latest live sets and will undoubtedly be part of their five-date residency at Zappos Theater inside Planet Hollywood Resort. It’s been a long journey for Hubbard and Kelley from meeting as students at Belmont University in Nashville to headlining Las Vegas, but if their current visibility and level of success is any indication, the career cruise is rolling on a full tank of fuel.

Planet Hollywood Resort, 8 p.m. Dec. 5, 7-8 & 11, starting at $49 plus tax and fee. 800.745.3000 Ticketmaster