Sadly I think he would still be gambling, smoking and drinking with out end.
Sid James had already had a heart attack in 1966, meaning he was replace by Harry H. Corbett in the lead role of, Carry On Screaming!
And there were only 3 films after his death, Carry On England, Carry On Emmannuelle and Carry on Columbus.
Patrick Mower feature in place of Sid James in Carry on England, so Sergeant Len Able would most likely be Sergeant Sid Albe.
I can not personally find a place for him in Emmannuelle and Columbus would be to late as it is filmed in 1992 (which only featured Jim Dale and Jack Douglas as the only recognisable stars)
As for Eastenders, what would his role be Land Lord with Barbara Windsor is two cliché especially trying to fit him in with the Mitchell brothers.
And would he still be going on stage at 72? Him dying on stage fitted his personality, the same as Tommy Copper?
I agree about the drinking, smoking and gambling. I agree that him living longer won't save the Carry On franchise. I didn't know that was how Harry H Corbett got screaming, but because he was so good in it I can't imagine James being better. For that matter I can't imagine James being better as Sergeant Knocker than Phil Silvers in Camel for that matter.
I wasn't serious about him being in East Enders, but what about Coronation Street, Emmerdale Farm, Brookside or even The Archers? He could have been Dan Archer. BTW, I'm not serious about any of those either, especially as Dan Archer was killed off in 1986.
East Enders started in 1985, ITTL James dies in 1986 and IOTL Windsor doesn't join the show until 1994 so they can't be landlord and lady of the Queen Vic anyway.
Having said that everyone seems to appear in a British soap opera these days. I don't know if it is true, but there is a story that in the 1960s Lawrence Olivier wanted to play a walk on part on Coronation Street. However, Norman Wisdom had a cameo in the show a few years before he died and Robert Vaughn has been in it too.
Plenty of actors work into old age. ITTL he could die on stage in 1986 having survived the 1976 heart attack.