While it is impossible b to predict alternative events anf not the place of this sub I will point out one thing.

Sumnter was not the only potential hot spot. You had Fort Pickens in Pensacola under siege. And if Virginia rebelled then as in fact Norfolk amd Fort Monroe were vulnerable too.

Sorry, but your submission has been removed because we don't allow hypothetical questions. If possible, please feel free to rephrase the question so that it does not call for such speculation, and resubmit Otherwise, this sort of thing is better suited for /r/HistoryWhatIf.