Is this the end of an era?

It seemed that way yesterday afternoon. After over a year of speculation, the Nets finally decided to turn over a new leaf and trade Jason Kidd, agreeing to deal him to the Dallas Mavericks along with forward Malik Allen for a package that included point guard Devin Harris, guard Jerry Stackhouse, center DeSagana Diop, forward Devean George, guard Maurice Ager, $3 million in cash, and first-round draft picks in 2008 and 2010.

However, the trade was nuked when George refused to consent to the trade — he’s one of the rare players with a no-trade provision in his contract. And without his $2.4 million salary slot, the trade falls apart like a house of cards.

So sure were the Nets of the deal that Kidd and Allen were held out of the Nets’ 109–91 loss to Toronto last night, while head coach Lawrence Frank spoke of Kidd in the past tense before the game.

“I love him. He’s a very special person, but it’s time for both him and the organization to part ways,” Frank said. “We’re giving up a Hall of Fame point guard and some good role players.”

Not so fast, apparently. But the deal could be revived if the Mavs include an old familiar face — Keith Van Horn. Though long retired, the Mavs still own his rights and could sign-and-trade him to the Nets as part of the trade to make the numbers work under the salary cap. Van Horn would get a $2 million golden parachute that he can use to buy a lifetime supply of knee-high black socks. However, doing so would cost the Mavs an additional $2 million in luxury tax — after the original trade already would have added close to $6 million — which his why Dallas owner Mark Cuban had avoided going that route in the first place.

In a separate deal necessitated by league roster requirements, the Nets had agreed to deal swingman Antoine Wright to Dallas for a second-round draft pick; that would only happen if the trade for Kidd is resuscitated.

The Nets were expected to buy out Stackhouse immediately, permitting him either to return to Dallas after a league-mandated 30-day waiting period or sign with another contender.

The Kidd trade may not be all the Nets are up to either — they also were rumored to be contemplating a Vince Carter-for-Jermaine O’Neal deal with Indiana. Regardless, if Kidd goes then Carter’s days here would appear to be numbered as well given his age (31) and the Nets now crystal-clear focus on the future.

Thus, the rebuilding is off to a quite a busy start. Within a week the two linchpins (Kidd and Carter) could both be gone, and the next generation of Nets in place. Or, stuff like the George veto could keep happening and the trade speculation could drag on interminably.

I’ve often said that Nets team president Rod Thorn has been better on the big deals than the small ones, and this would have been another example. The Nets would come away with far more than they had any right to expect, partly because Kidd’s reputation around the league hasn’t recalibrated to the reality of how he’s actually played over the past 12 months.

Had Thorn waited until summer the word might have leaked out, which is why acting before the trade deadline was of so much importance. Yet to his credit, he held out for a good deal and could still get it.

If this deal or something like it goes through, Harris will be the cornerstone. A blur-quick point guard who is coming into his own at 24, Harris is a poor outside shooter, kind of like Kidd. But he is one of the very best defensive players in basketball and is outstanding at drawing offensive fouls in particular.

Right now he looks to score more than pass when he drives, so some question his qualifications as a “pure” point guard. Nonetheless, he had a better Player Efficiency Rating (PER, my per-minute rating of a player’s statistical effectiveness) than Kidd this season, and only figures to improve it in coming seasons.

Currently Harris is nursing a sprained ankle, but he may be back after the All-Star break — which is the earliest he could plausibly suit up as a Net anyway.

Diop would be another important piece. Although his contact expires, he’s a very solid frontcourt defender whom the Nets would presumably have a strong interest in re-signing given his age (26) and the team’s frontcourt woes. Offensively, he looks really skilled if you’ve spent a half-decade watching Jason Collins, but as with Twin he’ll be out there for his help defense and be asked to stay out of the way on O.

Of course, the players are only part of the story. The Nets were looking for three things from any Kidd trade: young talent, cap relief and draft picks. I’ve said for a long time that Thorn would have to settle for two out of three, and it appears he compromised on cap space in his talks with Dallas.

Nonetheless, this would be an outstanding deal for the Nets, regardless of whether it’s George or Van Horn who’s in it for cap ballast. They’d certainly get young talent in the form of Harris; and the draft picks in 2008 and 2010 would be very helpful too. Harris is arguably better than Kidd right now and costs about a third as much next season; to get players, draft picks and cash in addition to that almost seems too good to be true.

As you can probably tell, I don’t understand the trade nearly as much from Dallas’s end. It denudes their bench, costs them several key assets for the future, and may allow Stackhouse to sign with one of their Western Conference competitors. Dallas envisioned this trade as the deal to put them over the top, but much like Phoenix’s misguided trade for Shaquille O’Neal last week I think it only puts them farther from the promised land. Maybe George’s nyet will prompt them to reconsider.

If it does go through, Nets fans shouldn’t mourn. It was the right time to go, as Frank said, and New Jersey fans can look back fondly on a great six-year run.

Kidd’s arrival at The Swamp made a laughingstock respectable and gave Nets fans a half-decade of alleyoops, excitement, and most of all winning. As I keep saying, there shouldn’t be any sadness about the inevitable fact that New Jersey had to trade him and rebuild. Thorn made a great deal when he brought Kidd here in 2001; in sending him out he seems poised to make another one.

jhollinger@nysun.com