In message , Bob Wood
writes

If relying on Pre-Pay, an Oystercard will never become a Travelcard.

[...]

It can never become a Travelcard because it can never be used on most
National Rail services.

Be cautious when saying "never"

In a few years, when Oyster is rolled-out across the NR network in
London, I suspect that it could do so - although perhaps the capping
arrangements will have changed by then.

(I suspect that you were using "never" in a rather more short-term sense
than the word implies).
--
Paul Terry