I think Queen Elizabeth has a lot of life left to live....she is healthy and has announced her intention to continue as Queen until she dies. Little by little, Charles has assumed some of her duties as age has slowed her down....but she remains active, alert as ever, and in complete control of all her remarkable capabilities.
If Prince Charles outlives her, and the UK retain the monarchy, then, yes, Prince Charles will be the next King.
Queen Victoria lived to be very old, and as a result her son was very old by the time he became King. But he did become the King and the people greatly loved him during his short reign.
I'm glad that the rights of succession are firmly established and that Charles will become the King. That will give William and his wife ample time to have some time to themselves, to have some privacy while they have their children, to spend time with their children, and to enjoy some time without all the responsibilities of the throne taking all of that away.
Charles will make a wonderful King.....all of his adult life, he has been tireless in his efforts to make better the lives of "small people". The Prince's Trust has given out millions of pounds to help people set up small businesses. The revitilization project in the Duchy of Cornwall has given thousands of people living in rural areas new jobs and incomes which were disappearing from their area....just as they have disappeared throughout rural areas all over the world.
He is one of the most generous personal philanthropists in the UK....and will continue his efforts during his reign to try to help the people in his realm.