With new signing Andrea Dossena and Fabio Aurelio more established internationals in Insua's position, the move may remain an outside possibility.
The 19-year-old Argentinean would most likely head straight into the Magpies' starting line-up ahead of Jose Enrique, who has failed to live up to his £6.3 million billing from Villarreal.
"I've got to sign another left-back, as I've only got one at the club," said boss Kevin Keegan.
"That's not to say I don't fancy Jose (Enrique), I do, but I need another left-back."