Mark Jones, 43, who had been in hospital since the incident on 26 July, died on Saturday.
Two men have been charged with attempted murder and having a shotgun following the shooting on New Road, Mountain Ash.
South Wales Police said a review of those charges would now take place.
Edward Bennett, 47, from Mountain Ash, and Stephen Bennett, 52, from Pontypridd, were both remanded in custody after appearing at Cardiff Crown Court in August.
Det Ch Insp Ceri Hughes said: "Our thoughts are with Mark's family who are being supported by a family liaison officer at this difficult time.
"A review of charges in relation to the two men in custody will now take place."

The final member of the family, a male marmoset called Gomez, was found by police on Monday, having been abandoned on a vets' doorstep.
A female and a baby were retrieved on Sunday, and are already back at Symbio Wildlife Park, south of Sydney.
Two men have pleaded guilty to charges of dealing with proceeds of crime.
Brothers Jesse and Jackson George are not believed to have snatched the monkeys from their enclosure, but they were charged with trying to profit from the theft.
Pygmy marmosets - the world's smallest monkey species - command up to A$5,000 (Â£3,000, $3,700) on the black market.
Police found the men after a tip-off from the public. A desperate appeal for information had been launched by the zoo, amid fears that the baby marmoset would die within 48 hours if unable to feed from its mother.
The four-week-old was found when the Georges' car was pulled over at Appin, southwest of Sydney.
The female marmoset was found about 20km (12 miles) away in the Campbelltown area.
Australian newspaper The Daily Telegraph said the brothers had exchanged marmoset pictures with a third person via mobile phone, along with messages about how much a monkey could sell for.
"Ay, check out my monkey," wrote the third person, according to court documents. "That's mad bro. Wanna sell it bruh?" Jackson George replied.
The baby marmoset is now home and well, said Symbio Wildlife Park, after they reunited it with its mother.
"Mum cradled the baby straight into her arms and bub immediately began to feed," the zoo wrote in a statement on Facebook.
Police say they are continuing their investigation into the theft.  The zoo said the marmoset enclosure is currently closed "to give the family privacy".

Bernard Hender, 19, and Doug McTavish, 39, died in the blaze above a funeral director's office in Llanrwst, Conwy county, in October 2014.
The Abergele inquest is examining if a Hotpoint dryer caused the fire.
On Thursday, a fire engineer told the hearing there was "no compelling evidence" it started in the dryer but he could not rule it out.
Clifford Christie, a member of the Institute of Fire Engineers, was asked to look into the cause of the fire by domestic appliance company Whirlpool.
Giving evidence on the second day of the hearing, he said the dryer was "severely damaged" by fire but some components on the machine were intact.
Mr Christie said he was "satisfied" it had not started in the timer, the motor or the drum, and there was no accumulation of lint in the machine.
But he said he could not rule out that it started in the machine's starter switch, which was not recovered following the blaze.
He also told the hearing it was possible there was a fault in an iron kept in the same room.
He said evidence given to the inquest on Wednesday that the iron was switched off might have been "mistaken".
On Wednesday, a tenant who lived in the flat spoke of surviving the fire.
Garry Lloyd Jones, 50, told the inquest: "I just remember walking down the corridor to see what was going on and seeing flames coming out of the tumble dryer.
"I went down to the living area and went to the kitchen and there was nothing there but when I looked out of the kitchen window I could see an orange glow."
Notices had previously been issued by Whirlpool telling customers to unplug Hotpoint, Creda and Indesit models manufactured between 2004 and 2015 after a potential fire risk was identified.
The inquest continues.
A man who was in a critical condition after a shooting in Rhondda Cynon Taff two months ago has now died, police said.
[NEXT_CONCEPT]
Three rare pygmy marmosets have been rescued and are set to be reunited, after being stolen from a Sydney zoo at the weekend.
[NEXT_CONCEPT]
A tumble dryer could "not be ruled out" as the cause of a flat fire in which two men died, an inquest has heard.