The Toronto Raptors are the latest victims of the LeBron James postseason tour, getting swept out of the playoffs by the defending champion Cleveland Cavaliers in commanding fashion. 

The Raptors have longed to be considered one of the elite teams not only in the Eastern Conference, but in the entire NBA. They've put back-to-back 50-plus-wins seasons for the first time in franchise history over the past two seasons.

The team reached new heights as DeMar DeRozan became a top-tier scorer, Jonas Valanciunas quietly improved and Kyle Lowry continued being an excellent all-around stat producer running the point. Unfortunately, the Raptors are now in serious trouble.

It took time for Toronto to bounce back from Chris Bosh's departure but they finally arrived back into relevancy. Now, there's should be serious concern within the franchise that the Raptors are close to being extinct once again. Here are three reasons the Raptors are in big trouble going forward. 

Lowry could be done with Toronto

Lowry may not get the star-billing that DeRozan does, but he's arguably the most important piece of Toronto's puzzle. Kyle could be ready to move on from that, opting out of the final year of his contract to test the free agent market.

"A ring. Nothing else. I just want a ring," Lowry told reporters of what he's looking for following the Game 4 sweep. 

The Raptors are a good team that, at times, even looks great. Are they a championship-level team, though? Not while LeBron is running the show in the East, and the Raptors are essentially stuck with the roster it has. 

DeRozan is set to pull in $27 million next year, while Valanciunas is due for $15 million and DeMarre Carroll rakes in $14.8 million. That doesn't leave the Raptors with much wiggle room for free agency, and why it's in Lowry's best interest to prepare to return to life in America. 

The Raptors will absolutely feel the sting of Lowry leaving, too. The 30-year-old point guard and three-time NBA All-Star just wrapped up the best season of his career. He averaged 22.4 points, seven assists and 4.8 rebounds.

He also shot over 41 percent from three-point range for the first time in his career, on a career-high 7.8 attempts per game. Another high-level team undoubtedly can't wait to try to add Lowry this summer, and it's hard to imagine him back in Raptors uniform once a contender comes calling.

More pieces on the move

Lowry isn't the only piece the Raptors may be without once the offseason smoke settles. Serge Ibaka is set to hit unrestricted free agency, which would be another big loss for Toronto. Ibaka was a major trade deadline acquisition for Toronto.

Ibaka averaged 31 minutes, 14.2 points, 6.8 rebounds and 1.4 blocks per game in the 23 contests he started in for Toronto during the regular season. He was an integral part of their frontcourt rotation and linchpin of their defense. 

Serge, making $12.5 million in the final year of his contract, will be one of the best available big men on the market. The Raptors would have to spread their finances incredibly thin to retain him, and even if they did, they'd then be salary-committed to a core of DeRozas, Valanciunas, Carroll and Ibaka.

That's not a bad core, per se, but it's not one that's going to unseat LeBron.  That's the same core that just attempted it, minus Lowry, and they didn't even come close really. More role players are also hitting free agency, like Patrick Patterson and PJ Tucker. 

The Raptors are going to have to re-tool their roster across the board, which is always a dangerous place to be. 

LeBron slammed their window shut

There's no telling how long a contender's window will stay open. For some teams, it's a one-time thing that they captured lightning in a bottle. For others, there's simply never enough lightning in the bottle to break out of said bottle. 

The Raptors have fallen in the latter category for years, and it may simply be time to admit defeat. They moved on from Rudy Gay, rebuilt around DeRozan and Lowry and came to the same sobering realization a team like the Indiana Pacers came to years ago.

LeBron's not only King of the Eastern Conference, but executioner. 

Like a guillotine to a neck, LeBron has seemingly slammed the window shut on the Raptors' contending days. James eliminated Toronto for the second year in the row, this time doing it in even more dramatic fashion.

There's simply no reason to believe that changes next year, even if the Raptors rolled out the exact same team. DeRozan hit a new career-high in points per game (27.3) and rebound (5.2) but couldn't come close to dethroning King James. 

There's no shame in it, either. Many teams have fallen to his sword, and the Raptors would be wise to take their ball and go home rather than making decisions that could set their franchise back for years just to roll the dice against LeBron one more time. 

The writing on the wall for Toronto doesn't look pretty no matter how you look at it. The stunning sweep at the hands of LeBron may have been the "big bang" that leaves this group of Raptors extinct.