No one would be being dumped. If that is how you feel then your own retirement will seem like a nightmare for you. What is happening is that folk are being given their well earned break, whilst others are given their chance to contribute. The older are not more important than the younger.
No one needs paid employment to feel useful. If they feel that they do, then they probably need help. Folk without a job remain useful as sources of knowledge general help. To think otherwise would condemn many housewives and househusbands onto the "useless" pile. And as mentioned, at some point every employed person has to call it a day and retire, it's just a matter of when.
One can not ensure jobs for all. At any one time there are fewer job opportunities than there are people able to fill them, unless one is advocating a regime whereby jobs are made up but have no real value, in order to make folk feel they are creating wealth for the nation. The reality is that those who have a job have to create enough wealth to cover the nation's bills for all citizens. Idealism is nice but we have found no way to ensure jobs for all yet.