You are irrelevant. People will want this because of the convenience.
(s)he may very well be irrelevant, but there are lots of people, governments and organizations out there that are not. The US recently sent $1.3 billion in cash to Iran as part of the nuclear weapons agreement/hostage release, or what ever it was. The point being that cash is not going away. Drugs, prostitution, government bribes(ahem, campaign donations), etc. If any government feels that Apple Pay is going to take away cash, it will be declared illegal. Besides, do you really think the US, or any government is going to allow Apple to take away their ability to print more cash?