The Kiwi star has been linked with retirement or a move to England at the end of 2016. But according to fellow New Zealander Nightingale, Marshall has plenty left to offer.
“He is only 30 now and plenty of halves play a lot longer than that so I think Benji has a lot of kilometres left in his legs,” he told the Dragons website.
“The way he carried himself (in 2015) was awesome so news of any retirement is speculation.
“I think he will improve more this season – I’m looking forward to seeing what he does.”
Nightingale is keen for the playmaker to stay with the Red V.
“There’s always going to be that sort of speculation when someone is off contract but Benji has definitely got a number of years left in him.
“Two years ago I think he had a cruisy year in rugby and came back and played the back half of the season so that will add to his longevity.
“He was in the top five for try assists last season and for a team that didn’t score a lot of tries it’s a pretty good effort.”