The 37-year-old's contract with the 20-time English champions has now been officially terminated, with the recent interview that he gave to Piers Morgan forcing the club to act.
Ronaldo had a contract with Old Trafford until next summer, and Man United are believed to have always planned to keep hold of the Portugal international until the end of the season before bringing in a replacement for the former Sporting Lisbon youngster.
However, with the Portuguese now departing, the Red Devils are short of options at centre-forward, especially considering Anthony Martial's injury problems this season.
According to the Daily Mail, Man United are currently discussing whether to replace Ronaldo in January or wait until the end of the campaign to bring in their desired target.
The report claims that senior figures at Old Trafford met on Tuesday to discuss the situation, and it is also possible that the club could bring in a forward on a short-term basis.
The Red Devils signed Odion Ighalo in January 2020, with the Nigerian scoring five times in 23 appearances for the club during a loan spell.
A similar deal to the end of the campaign is allegedly being considered, which would allow the club to then bring in their desired target during next summer's transfer window.
Napoli's Victor Osimhen is believed to be high on the club's shortlist, although it would be impossible to sign the Nigerian in the middle of the campaign.
PSV Eindhoven's Cody Gakpo is also being strongly linked with a move to Old Trafford, with the forward coming close to joining the club during the summer transfer window.
Man United's wage budget has been reduced by £500,000 a week due to Ronaldo's exit, opening up funds to make a forward signing at the start of 2023.
Marcus Rashford is the team's leading goalscorer in all competitions this season, finding the back of the net on eight occasions, while Martial has four despite his injury problems.
Bruno Fernandes, Jadon Sancho and Antony all have three goals, meanwhile, and the club will be competing on four fronts in the second half of the 2022-23 campaign.
Roma's Tammy Abraham and Barcelona's Memphis Depay have also been linked with moves to Old Trafford, with both players potentially available for transfer during the January window.