I don't think he will quit now as he is going to show everyone this season why he is the best driver. The FIA trying to prevent him from winning the 8th title is going to drive him to that title and will retire once he has done this. Hunger and passion has nothing to do with it and why he is more driven than anyone else on the grid this year. Driving a formula one car is different to other sports as it is more mental than physical even though you need to be super fit. Serena should have retired as leaving when you are at the top is what makes you great and remembered for what you have accomplished. Hanging around more in hope is tarnishing her name and her career. This is why Hamilton will win this season and retire.
I understand what you are saying and this is how it should happen, but you can never be sure of anything, so we have to wait and see. If Hamilton has some pride left in him, he will show his face and start fighting.
About Serena ... what can I possibly say that has not been said already. She's prolonging what is inevitable and with every year, with every tournament she's deleting the good results she has been able to achieve. I guess everyone remembers her as the one who could not let go already and not in a good way.