Celtic have been linked with a move for McGinn for quite some time and Rangers coach Thomson gave his verdict.
Rangers coach Kevin Thomson has claimed on BT Sport that a move for ex-teammate John McGinn to Celtic is "inevitable", despite the Hoops having two bids rejected for the Hibernian midfielder.
The Daily Record claimed Celtic made an initial offer of £1.5million before increasing that figure to £2million, but remains some way apart from Hibs' valuation of the Scotland international - which is said to be £3million.
McGinn, 23, is touted as a possible long-term successor for Celtic skipper Scott Brown, who is now 33 years of age and in the final year of his contract at Celtic Park. Brown, too, moved to Celtic from Easter Road.
Thomson, who played with McGinn during a short spell at Hibs in 2016 before becoming a youth coach at Rangers earlier this year, claimed that he expects a move to eventually be completed. He also reckons Brown will sign a new deal.
"I played with John and he's a terrific talent," Thomson said. "He's a powerhouse, he's a great lad and his feet are grounded. He comes from a great family which I think is really important.
"I think it is inevitable that he is going to go. Is he good enough to play in the side at the moment? Scott Brown is going nowhere, he might sign a new deal. Callum McGregor has been absolutely fantastic.
"The quality Celtic have got throughout their squad makes it difficult for any player coming in. But if you're a young player, and you get an opportunity with one of the big clubs, it's hard to pass up."
Brendan Rodgers told the Daily Record that he believes a deal will be difficult to complete for McGinn, after having two bids knocked back by Neil Lennon's side.
Other than Brown and McGregor, Celtic also boast Olivier Ntcham and Koussi Eboue in the middle of the park but a space could become available after offloading Stuart Armstrong to Premier League side Southampton.