While I'm not in this situation, I don't see much point in getting a credit card prior to retirement for points collection purposes (I can see why you'd get it for other benefits — perks such as travel insurance & cash flow management).
Say you get a card that earns 1pt per dollar. Even if you put a huge amount (for a retired person) of spend on it (eg $100K pa), you're getting a measly 100K points. On Qantas, that will barely get you one way to the US in J and not even all the way to Europe. And you're probably paying up for those points in the form of a hefty annual fee. Sure, some points earning is better than a poke in the eye, but it barely moves the needle.
Outside of churning, points earning through credit cards is a bit of a losing exercise imo.