Once considered a slam-dunk, the move of the New Jersey Nets from the East Rutherford to Brooklyn is now on shaky ground, thanks to local opposition over Atlantic Yards and a faltering real-estate economy. They could stick it out in the Meadowlands for a while longer, as their lease doesn’t expire until 2012.

Or, they could avoid further lame-duck status in Jersey and go back to where they came from: Nassau Coliseum, to be co-tenants with the New York Islanders.

A refurbished Coliseum is part of the Lighthouse Project, the pride and joy of Islanders owner Charles Wang and his partner, Long Island real estate whiz Scott Rechler. Like Atlantic Yards, the Lighthouse would be a commercial, sports and real estate complex with a strong component of affordable housing. Unlike Atlantic Yards, it is priced at $2 billion.

Granted, it has been years since I was on the junior high math team, but I’m still good enough with figures to know that $2 billion is a lot less than $4 billion. The problem is that the Lighthouse is going nowhere fast, following the glacier’s pace that many Long Island projects take. A commitment from the Nets could give it the oomph it needs.

Probably a longshot. For one, current Nets majority owner Bruce Ratner would sooner sell than shack up with the Islanders as a co-tenant — unless he can engineer a sweetheart land-development deal with the help of Rechler, that would include building a new arena. In that case, the whole deal might turn inside-out, with Ratner not only bringing his hoops team to Long Island, but also buying the resident NHL team, thus relieving it from Wang’s inept stewardship. Stranger things have happened.

But then, Ratner has other options. There’s always Newark and the shiny new Prudential Center, where the Devils would welcome a reunion with the Nets. Again, it’s not likely that Ratner would want to occupy a building he doesn’t own/control, so maybe he sells the franchise to Devils owner Jeffery Vanderbeek.

Or, if he’s going to sell, perhaps a buyer in Seattle would be interested, since there’s now an opening for a SuperSonics 2.0.