The Knicks’ draft pick next week, as well as any moves made during the summer, should mark the beginning of the end for the Isiah Thomas era in New York.

That may seem counterintuitive since Thomas’s reign has been marked by so many high profile moves that we’ve come to expect it will end with a bang, not a whimper. However, Thomas has weathered the fallout that followed last December’s brawl during the Knicks-Nuggets game at Madison Square Garden, he’s muddled through calling the fans names, and he’s survived a sexual harassment lawsuit. Tack that onto a job performance that has included one of the worst seasons in franchise history and salary cap mismanagement that borders on scandalous, and it should be clear that bullets won’t kill this regime. It will have to die of natural causes.

Those causes are approaching faster than anyone realizes. By this time next year the Thomas administration will have had four-and-ahalf seasons in office, and it’s entirely likely that a 42–40 record and a quick and dirty playoff dismissal by their cross river rivals will be all the team has to show for it. Thomas could be a darling of the press and that track record wouldn’t save him; and of course, Thomas is instead a lightning rod for everything that is wrong with the Knicks. I’m assuming that the Knicks will improve slightly again but not enough to be a contender, even in the Eastern Conference. After next season, Thomas will almost certainly realize that he has reached a point of diminishing returns in this position and jump ship to another hoops job where he can start over.

Two assumptions underpin my scenario. For one, I don’t think the Knicks will score one of the big name superstars on the trade market this summer; and for another I think that the Knicks’ improvement will be muted by an uptick in the entire Atlantic Division.

There is an unusual number of franchise players looking to change addresses this summer, but none of them are likely to wind up in Manhattan. To acquire Kobe Bryant, Kevin Garnett, Jermaine O’Neal, or Vince Carter, the Knicks would have to trade almost every young player with value as part of the exchange. That would result in a roster construction of a newly acquired superstar plus aging point guards (Stephon Marbury and Steve Francis) and a smattering of guys just above Development League caliber. That’s the scenario that most of the superstars on the block want to escape.

Meanwhile all of the Knicks’ divisional opponents figure to improve markedly. Division champion Toronto will have another summer to raid the European leagues for talent, and its no. 1 draft pick from last season, Andrea Bargnani, should build on his late season improvements. The Nets will probably find some creative means of keeping Carter or getting value for him in a sign-and-trade, and they will get their power forward, Nenad Krstic, back from an injury-marred campaign. Even without the top pick in next week’s draft, Boston figures to get better as forwards Al Jefferson and Gerald Glass and point guard Rajon Rondo mature, and with the no. 5 pick, it should land an impact player. Philadelphia played substantially better during the second half of the season, and, it, too will add a young impact player in next week’s draft.

So without a big name superstar and against better divisional foes, the Knicks will face a tough road next season. With better overall health — particularly injury-free seasons from shooting guard Jamal Crawford and power forward David Lee, as well as continued improvement from forward Renaldo Balkman and guard Nate Robinson — I can see the Knicks adding five to seven wins over last season’s 33–49 mark. But that will leave them around 40–42 and looking at another year of small, incremental improvements. This will feel particularly painful to the Garden faithful as teams that even Knicks fans could look down on, such as Chicago and Toronto, move into the Eastern Conference elite.

In fact, one plausible scenario is that the Knicks do make the playoffs and then get a resounding firstround thumping from a Chicago team aided by the players drafted with the picks Thomas traded to the Windy City. That would grease the skids for Isiah’s exit. Act I will have been his rapid dealing for big names like Marbury, Francis, and coach Larry Brown. Act II will be muddling through and coaching a group of youngsters to improve a bad team into a mediocre one. The last act is the plateauing of that team, which is what will happen over the next 12 months.

But what then? Bringing in a retread like John Gabriel (who was rumored to have the inside track on the Seattle GM job before ownership intervened and hired Sam Presti) or local favorite Kiki Vandeweghe, would be problematic, as conventional thinking is exactly what got the Knicks into this bind. Thomas and his predecessor, Scott Layden, both ignored the longterm realities of the salary cap, and the fans have suffered through seven years of forgettable basketball as a result. The next Knicks GM should come from the ranks of a successful team’s front office, ideally Phoenix or one of the Texas teams, and have a good grasp of the cap and scouting techniques. He or she will inherit a good base of young talent and available cap room a year away, in 2009, but little wiggle room to satisfy a fan base that is justifiably impatient after the machinations of two bad regimes in a row.

mjohnson@nysun.com