The Belgium keeper has been on loan at Atletico Madrid since 2011, and played an important role in Los Rojiblancos' 3-1 triumph over the Blues in the Champions League semi-final second leg on Wednesday night.
Speaking to Sky Sports News, Neville said that while Petr Cech is still an excellent shot-stopper, Courtois is "somebody special".
He said: "I would say it would be harsh on Cech. He was voted by the PFA, his fellow players, as being the best goalkeeper in the league this year - and I actually put him in my team of the season.
"But if you are talking about the future and grabbing a goalkeeper back who is going to play for you for the next 10 to 15 years then he just looks a massive talent.
"I think they would have to [bring him back] and that would potentially be harsh on Petr Cech because I think he's a top goalkeeper. He's maybe not at the level he was at in 2005, but still a very good goalkeeper. However, they look like they've got somebody special there."
Atleti will meet local rivals Real Madrid in the final later this month.