It won’t be the “homegrown Americans”, but more like the radicalized imports, sleepers who’ve snuck across (your links), left-wing wackos, America-hating muzzies... the list is unsettling, to think they’re already here and ready to go upon command.
Nidal Malik Hasan, the Fort Hood mass murderer was homegrown here in the U.S.A. You can’t take the jihad out of the muzzie, it’s in their DNA.
OTOH, if finally every “infidel” American comes to regard every recognizable muzzie in America as a jihadi waiting for the right moment to strike, or as a jihad enabler, the islamic brethren might not find their murderous mission to be all that easy.
Simple litmus test: say just three words, “Jesus is Lord!” and gauge the muzzie’s reaction.