As the Queen becomes increasingly frail in future years I can see Charles presiding over these PC meetings, though.
Personally I think these will be one of the last things the Queen gives up, they take place at Buckingham Palace or Windsor Castle so basically at her 'house', they don't last forever and the Queen merely says approved to each item read out at a meeting organised by the President of the Council. To me even if the Queen is too old or infirm to go out and about she would need to be on deaths door and a regency declared before she gave these up.
I can see Charles doing more of the engagements, overseas travel, audiences etc but this is one of those events that make up the Queen's constitutional role which she no doubt sees as important so she will do it until she is utterly incapable of doing so.