That’s according to a report from Football League World, who suggest that the midfielder could find himself out of Neil Warnock’s plans entirely on Teesside.
Wing enjoyed a promising campaign for Boro last term, but drifted out of the starting XI in the early stages of this season, and ultimately had to move to the Millers to seek first team opportunities in January.
Since then he has made nine Championship appearances, including eight starts, registering one assist in the process.
Wing has slipped behind Sam Morsy, Jonny Howson, Paddy McNair, and George Saville in the pecking order at the Riverside, and it is claimed that a number of Championship clubs would be keen on snapping him up if Boro decide to sell this summer.
Whether Rotherham are among those vying for his signature remains to be seen.
Elsewhere, Noel Whelan has argued that young Leeds United midfielder Mateusz Bogusz may need a loan to the Championship to realise his potential as a Premier League-quality talent.
The Polish teenager has made just three senior appearances for the Whites since arriving at Elland Road in January 2019, and is currently enjoying a temporary stint with LaLiga2 outfit UD Logrones, where he has registered one goal and one assist this term.
But Whelan believes that the key to him kicking on even further could be for him to experience the cutthroat physicality of the Championship.
Speaking to Football Insider, he said: “You get that little bit of experience, you do well there and then you’re looking for your next challenge. Championship football would be a step up.
“It will be beneficial for him and it will be beneficial for Leeds. If he keeps showing that he can do it at different levels then he’s got the chance of proving he can do it at Premier League level.”
Bogusz himself has admitted that another loan is a real possibility, telling LUFC Fan Zone: “I think I will still go on loan next season because the team plays very well.
"They play in the Premier League and I think I’m not ready to play in the Premier league or to just be a sub.”
We’ve gathered the rest of today's Championship speculation below:
1. Wing facing uncertain future
On-loan Rotherham United midfielder Lewis Wing is facing an ‘uncertain future’ at his parent club Middlesbrough. (Football League World) (Photo by Jan Kruger/Getty Images) Photo: Jan Kruger
2. Leeds player tipped for Championship loan
Leeds United midfielder Mateusz Bogusz needs a Championship loan to become a Premier League standard player, according to Noel Whelan. (Football Insider) (Photo by OLI SCARFF/POOL/AFP via Getty Images) Photo: OLI SCARFF
3. Phillips urges Wilson to move
Kevin Phillips has urged Harry Wilson to leave Liverpool permanently in the summer and suggested Cardiff City would love to bring him back for next season. (Football Insider) (Photo by George Wood/Getty Images) Photo: George Wood
4. Potential update on Morrison contract
Ravel Morrison was not training with Sheffield Wednesday on Thursday, casting fresh doubt over whether he will be given a contract with the Championship strugglers. (Yorkshire Live) (Photo by Paolo Bruno/Getty Images) Photo: Paolo Bruno