The 28-year-old, who has hardly featured since suffering a serious knee injury in March, will not be "rushed" back, according to Boothroyd.
"We rushed him and that's had a big detrimental effect on him. We're paying the price for that. I wouldn't want to put him under any pressure but we're now talking next year, definitely," Boothroyd told the club's official website.
"We've got to make sure he's 100% and when he is ready to come back, that we've done everything we can to make sure he doesn't break down again."
Langmead has been with Northampton since 2012.