New challenge now faces the Celtics: Can they repeat as world champs?

The duck boat parade that cruised through the jam-packed streets of Boston on Friday was the official capper on the Celtics’ quest for Banner 18.

The players, whose march through the playoffs lasted two full months, now will split off to their respective offseason homes for some well-deserved time off. But despite being just days removed from the NBA Finals, at least some are already thinking of what comes next: A bid to go back-to-back in 2025.

“Hopefully it’s a burden off of their shoulders,” veteran guard Jrue Holiday said after Monday night’s championship clincher, referring to superstar teammates Jayson Tatum and Jaylen Brown. “But another burden is doing it again.”

Repeating has proven difficult in the modern NBA, which now has greater parity and is less reliant on Big Three superteams than it was in the previous decade.

The last team to win the Larry O’Brien Trophy in consecutive seasons was the Stephen Curry-led Golden State Warriors in 2017 and ’18. No champion since then even reached the conference finals the next year.

A lot will need to go right for the Celtics to buck that recent trend and win it all again next June. But after years of falling just short of its ultimate goal, the championship window for the fabled franchise now is wide open.

Barring some sort of major offseason surprise, the Celtics should enter the 2024-25 campaign as clear title favorites.

Every Celtics starter and seven of their top eight rotation players (Tatum, Brown, Holiday, Derrick White, Kristaps Porzingis, Al Horford and Payton Pritchard) are under contract for at least one more season. The eighth, off-the-bench shooter Sam Hauser, has a $2.1 million team option for 2024-25.

Five of those eight players will be in their 20s when next season tips off. White turns 30 in July. Holiday (34) and Horford (38) are the vets of the group, with the latter planning to return for an 18th NBA season after winning his first title.

“We’ve got some guys who are getting up there a little bit, (but) basically we’re a young team,” Celtics co-owner Wyc Grousbeck said this week on WEEI. “Most of our players are 30 or younger, and that is bad news for everyone else, hopefully.”

Boston’s impending free agents (Luke Kornet, Xavier Tillman and Svi Mykhailiuk) played a grand total of 234 minutes this postseason, and that number would have been much lower had Kornet and Tillman not needed to fill in for an injured Porzingis.

The Celtics also have a $2.2 million team option for Neemias Queta, and Oshae Brissett has a $2.5 million player option. Both played sparingly in the playoffs, with Brissett seeing non-garbage time minutes in just two of Boston’s 19 playoff games and Queta playing only in blowouts.

There will be some inevitable shuffling around the fringes of the Celtics’ roster. Some extra frontcourt depth would be useful, for instance, with Porzingis needing offseason surgery to repair his “rare” leg injury and Horford pushing 40. Perhaps they’ll look to target a prospect who fits there with their first-round pick (30th overall) in next Wednesday’s NBA draft. (Yes, the NBA holds its draft just a week after the Finals conclude.)

But unlike nearly every recent NBA champion, Brad Stevens and Co. won’t need to worry about replacing any core components of their masterfully constructed machine. The biggest roster-related offseason news to watch for, then, involves a couple of players who are set to hit free agency next summer.

Tatum, who made first-team All-NBA for the third straight season and then led the Celtics in points, rebounds and assists in the playoffs, now is eligible to sign a five-year, $315 million supermax extension that would be the richest in league history. It would be stunning if he did not do so this offseason, anchoring himself to Finals MVP co-star Brown (who signed a similarly massive deal last summer) and the Celtics for the foreseeable future.

White isn’t in that same financial stratosphere, but he’s up for a four-year extension worth up to $127 million. Stevens has said multiple times he wants to keep White around long-term, and The Athletic’s John Hollinger reported the Celtics are “strongly interested” in re-upping the two-time All-Defense selection ahead of his contract year. A White extension is “very likely,” per Hollinger’s report.

The Celtics also could choose to decline Hauser’s option and instead sign him to a longer-term contract. The 26-year-old 3-point ace was inconsistent in the playoffs but played well on both ends of the floor in the Finals.

The money shelled out to assemble the NBA’s deepest roster will eventually hamstring the Celtics, who could face some onerous salary cap penalties heading into the 2025-26 season. For at least one more year, though, they should be able to trot out a nearly identical team to the one that just bulldozed its way to an 80-21 record (playoffs included) and ranked among the best statistical squads in basketball history.

Will that roster be able to successfully navigate an Eastern Conference that isn’t brutalized by injuries to nearly all of its non-Celtic star players? After all of those teams spend an offseason cooking up ways to stop Joe Mazzulla’s uniquely devastating scheme? Will the Celtics themselves be able to stay as generally healthy as they were this season, Porzingis’ playoff absence notwithstanding?

Recent history suggests the answer to at least one of those questions will be “no.” But these Celtics have every ingredient necessary to repeat.