Rashford scored 14 goals and provided 10 assists for Barca in all competitions this season as he shined under manager Hansi Flick on loan from United.
Barca beat Real Madrid earlier this month to win the Spanish top flight with three games to spare and retain the title, a feat that Rashford will only want to build on as he seeks a permanent move.
The England star could be signed by the Catalan club on a permanent basis for just £30M but as negotiations continue, a move is looking increasingly unlikely.
Speaking to ComeOn, Stam believes Rashford could stay at United, a move he thinks that many would be happy with.
“Marcus back to Man Utd? You never know. If you look at Marcus, I've always said, even when he was at United, he's potentially a fantastic player, because he's got pace, which is something every striker needs nowadays. Technically, he's good.
“For Marcus to go back to United, I think a lot of people would love the idea. I think it's good to have him back within the squad because he's an asset for United. Probably other people would say, 'Well, he tried it; he left us, and we don't want him back.'
“But for myself personally, I would like to see him back. I think it's also good because if you look at the squad now, okay, they've made some great transfers and brought some great players in, but you need to have some extra quality, I think, also in the wing positions, too, when something happens, when there are injuries, when there are suspensions, or when somebody is not in good shape.
“Marcus would be a very good asset for the team.”
Barcelona have until June 15 to activate their option to sign Rashford and must act fast if they are to snap him up before the season begins.