The Cottagers lost Mousa Dembele and Clint Dempsey last summer but have still enjoyed an impressive campaign and could yet secure a top-ten finish.
Riether, who is on loan from Cologne but is expected to make the move permanent in the summer, believes Fulham's top performers could well attract attention when the transfer window reopens but expects the club to progress under the guidance of Martin Jol regardless of who departs at the end of the campaign.
"At Fulham it is always possible that you might lose great players, big players, to other clubs, so it is not easy," he told the Evening Standard.
"It is normal that if you play well other clubs want to buy you.
"If some players do leave, other good players will come and I think Fulham will have a great team next year."
He added: "There will be a lot of changes in the team this summer. Some new players will join, some players will leave but we will be prepared for next season."