The 30 year old St George Illawarra playmaker, who turns 31 later this month, is unsure if he'll be offered a new deal by the Dragons despite being keen to stay with the club.
"I'm a realist and knowing that rugby league's a business and there's always going to be a chance that you're going to have to move on," Marshall said.
"In my situation, coming on 31, there's a lot of younger guys around the club that can lead this club in the future.
"My priority is to stay here but I'm understanding that there might not be a chance of that happening."
Marshall maintains he has two to three more years left in him at NRL level and plenty to offer young playmakers.
"The good thing about the kids here is everyone's willing to learn and listens and takes on board anything you say," he said.
"I do enjoy the coaching side of things and mentoring side of things. This is my 14th season - it's not like I've just started - I've got a lot to offer."