[magicalhippo]

As noted, the discussion between Wheeler and Feynman was in 1940, long before the development of the Standard Model[1].

In the Standard Model there is a sea of virtual particles in the nucleus, but they're virtual and hence not real in the sense that the positron in the One Electron model would have to be. At least that's my understanding.

Also, electrons can travel over large distances, CRT monitors do that all the time for example. So I'm not entirely sure how Wheeler imagined hiding the positrons in the nucleus would solve the whole positron problem.

[1]: https://en.wikipedia.org/wiki/Quark#History