Stanton, a former England schoolboy international, has made 264 starts for the Iron since making his debut in the 2-0 FA Cup first round loss to Rushden and Diamonds in October 1999.
Although he scored just once, in the play-off semi-final against Lincoln in 2003, he has been a regular in the side - but has seen injury limit his chances.
Last year he featured 23 times, bettering that by just two this season.
With Musselwhite and Evans leaving United's only goalkeeper is currently teenager Josh Lillis - who has yet to feature at all in the first-team.
Johnson has already agreed a move to Tamworth, while Musselwhite is in talks with Conference South side Eastleigh.
Wayne Corden is likely to join Leyton Orient, who he spent the end of last season with on loan.
The remaining eight players out of contract have all been offered new deals to stay.
Matty Sparrow has been offered a two-year deal, with an option to extend it to a third season.
Lee Ridley, Andy Crosby, Cliff Byrne, Steve Torpey, Ian Baraclough, Peter Beagrie and Neil MacKenzie have all been offered single-year contracts.
Iron manager Brian Laws told the official website: "I expect answers from the players as quickly as possible, and have asked them to do that.
"There are some players who I've offered reduced terms to because I need to spread my budget as best I can, which will allow me to bring in some new players."