Back in October, the NBA's 2017-18 regular season was spoken of as a mere formality, a six-month prelude to a playoffs that would inevitably lead to the fourth straight NBA Finals pitting the Golden State Warriors against the Cleveland Cavaliers.

And we still may get that. Despite LeBron James and company's roller-coaster season and first-round struggles against the Indiana Pacers, and despite the fact that the Warriors don't look like quite the same team since Steph Curry's injury, it shouldn't surprise you in the least if it's June and the NBA universe is again focused on Golden State and Cleveland.

Yet, as this wild first round has reminded us, Warriors-Cavs Part IV is far from a foregone conclusion. The dynastic grip the two-time champ Warriors and their foil Cavaliers have had on the NBA the past few seasons feels much looser during this first round. As the Warriors' injury woes have reminded them that greatness can be fragile, and as the Cavaliers' struggling supporting cast has reminded LeBron that he can't do it all by himself, a group of other emerging NBA powers has risen up. If those powers don't compete for the title this season, they will soon enough.

And I'm not just talking about the Houston Rockets and their microwave offense that's statistically among the greatest of all time, or their James Harden/Chris Paul backcourt that could someday be remembered as the greatest backcourt duo of all time.

I'm talking about the NBA's youth movement that has been one of the great story lines of this season and the most fun story line of the first round of these playoffs.

I'm talking about Joel Embiid and Ben Simmons, turning the Philadelphia 76ers from league laughingstock a few years ago into legit title contender this season. I'm talking about Donovan Mitchell and Rudy Gobert, two draft-day steals who've turned the Utah Jazz from Gordon Hayward's jilted lover into one of the most fearsome defensive teams in recent memory under the tutelage of Quin Snyder. About Jayson Tatum and Jaylen Brown, two precocious youths who've turned a Boston Celtics season that has twice seemed lost due to injury (Hayward in the first game of the season, and then Kyrie Irving later) into a prelude for what should be one of the powers of the Eastern Conference for years to come. About versatile, transcendent 7-footers -- Giannis Antetokounmpo, Anthony Davis, Karl-Anthony Towns, Embiid -- whose presence in these playoffs (and, in Giannis' and Davis' case, whose dominance in these playoffs) has been both a joy to watch and a precursor to the future of the NBA.

But these playoffs mark something bigger than just seeing a bunch of youngsters showing out in the biggest spotlight of their young careers.

These playoffs mark the official beginning of the transition from one era of the NBA to the next.

We'll name the current era the LeBron Era, because eras are named after their single-most dominant character. But this era of the NBA has been about much more than LeBron. It's been about the Warriors' perfecting a brand of beautiful basketball that's forever shifted the philosophies of this sport. It's been about the San Antonio Spurs' continued dominance well into the twilight of Tim Duncan's career. It's been about the unlimited excitement and unrealized potential of Lob City. It's been about the frenetic energy of Russell Westbrook's game; even if you think his statistical profile has unnecessarily inflated his worth, there still has never been a player like him.

It's been, unquestionably, the best era of the NBA since Michael Jordan was winning six titles in the 1990s.

Yet what have we seen so far these playoffs? We've seen plenty of signs that this era is coming to an end. We've seen LeBron's team struggle in the face of an Indiana Pacers team that's more balanced and more knitted together than the Cavaliers, who very well could fall apart in the offseason if James leaves. We've seen Westbrook sonned by a rookie, Donovan Mitchell, who could be in line to take the 2016-17 MVP's mantle as the NBA's most exciting player, as he's helped his franchise rise from the post-Hayward ashes. We've seen what feels like the end of the Spurs' cycle of dominance, illustrated most poignantly by the dysfunctional handling of Kawhi Leonard's injury. We've seen the Sixers arrive, a year or two ahead of schedule. We've seen the most fun, most competitive series of the first round being between two Eastern Conference teams whose futures are as bright at the 76ers: the Celtics and the Bucks. Heck, we've seen signs that the top of the East might slowly be on its way to passing the West as the stronger of the two conferences.

And even though the Warriors obliterated the Spurs, we've seen holes poked in the air of inevitability that surrounded this team heading into the season: via injuries, via the decline of Draymond Green, via boredom.

In sum, we've seen our first playoff glimpse of what the NBA will look like post-LeBron Era.

And it couldn't be more thrilling.

This is not to say the LeBron Era is over. Even though it feels unlikely now, LeBron could will his Cavs into the Finals, reaching an absurd eighth Finals in a row -- he is, after all, still LeBron. And the Warriors certainly could cruise past the Pelicans and then the Rockets in search of their third title in four years.

But if that does happen, do not mistake that as a reason why this current era of the NBA will continue for several more years. It won't.

We're watching the beginning of the end of this era. Which is sad, in a sense, because this has been among the most thrilling eras in NBA history, and endings are always sad. But with the bevy of young stars on the horizon, this next era could be just as thrilling. Transitions from one era to the next are never easy. But these playoffs have shown us that the NBA has a clear line of succession once The King's era is no longer the king.