Ronaldo is desperate to leave the club after they failed to qualify for the UEFA Champions League following a sixth place finish in 2021/2022 season.
Suitors for the Portugal captain are few and far between, with the likes of Chelsea, Atletico Madrid and Bayern Munich all distancing themselves after being linked.
Ronaldo scored 24 goals across all competitions last season and new United manager Erik Ten Hag maintains the five-time Ballon D'or winner is part of his plans.
Ronaldo appeared as a second half substitute in Manchester United's opening game of the season against Brighton and Hove Albion while he also started the 4-0 loss to Brentford over the weekend.
Reports have emerged that the Red Devils are now ready to sanction the former Real Madrid and Juventus forward's exit but Neville feels that will not augur well for the club.
"I think there's a massive decision they have to make on Cristiano Ronaldo and they're damned if they do, damned if they don't," he said on Sky Sports' Monday Night Football.
"A few weeks ago before the season started, these two results, [the] best thing to do was facilitate a move out the club for Cristiano because he's obviously not happy and the club aren't happy with him.
"The problem they have now is if they lose him, there's nothing left in terms of the goalscoring part of the pitch and I genuinely think if they don't bring players in or if they bring in poor players in and he leaves, I genuinely think they can finish in the bottom half of the table.
"That's a bottom half of the table team, that's a massive statement."
