Since Paul was the apostle to the (Gentile) Church, who are his successors???
It is interesting to note that Cephas here could refer to Peter, in which case Paul is specifically condemning the apostolic succession that would be claimed by later Roman Catholics. But even if it is a different Cephas (unlikely), the rest of the passage makes clear that Paul condemns any succession other than from Christ to the believer.
Exactly, Peter was an apostle to the Jews. Catholics seem to ignore this very basic fact.