Sources: Jeremy Lin return uncertain

It has been a foregone conclusion for months that Jeremy Lin will re-sign with the New York Knicks, but sources close to the situation say the return of the free agent point guard is not as certain as it once seemed.

While both Lin and the Knicks are hoping for a reunion, sources say that if any clubs offer Lin, a restricted free agent, a backloaded contract that pays him an eight-figure salary in the third and fourth years, the Knicks could be given pause about matching the offer.

With the new collective bargaining agreement employing a more punitive luxury tax, beginning in the 2013-14 season, the Knicks are extremely concerned about the financial ramifications of such a deal.

Toronto is perhaps the only team that might consider offering Lin a backloaded contract, known as a "poison pill" deal. The Raptors are currently going all-out to sign Steve Nash. Toronto has offered Nash a three-year deal worth $36 million, sources told ESPN.com's Marc Stein.

But if Nash, who is also considering Phoenix, New York, Dallas and Brooklyn, rejects Toronto's offer, the Raptors may turn their attention toward Lin.

The Knicks can offer Lin a four-year deal worth $24.5 million. But an opposing team can offer Lin a poison pill that could go as high as $40 million over four years. Such a contract would pay Lin $5 million in each of the first two years and then go as high as $15 million in each of the last two years.

Matching such a contract would give the Knicks four players -- Lin, Carmelo Anthony, Amare Stoudemire and Tyson Chandler -- making more than $14 million in the 2014-2015 season. Those four players alone would have a combined salary of $72 million, nearly $2 million above the luxury tax.

While it may be doubtful that a club goes as high as $15 million in a season for Lin, even if one offered Lin roughly $10 million in the third and fourth years of a contract, the Knicks would be cautious about matching, according to a source.

Toronto, Dallas and Brooklyn have all expressed interest in Lin, according to sources, though he is a backup plan for each of the clubs.

The Knicks have said they plan to let the market dictate Lin's value, so they have not offered him a contract yet. With the ability to match any offer he receives, they plan to wait and see what Lin commands as a free agent. They just hope he doesn't command too much.