Yeah, there will be crackdowns. I expect stricter gun laws, more surveillance and so on... you know, the usual. However I do expect some pushback from paranoid Qtards and loonies, growing ever more twitchy, which will in turn feed back into the government cracking down even more.
A similar feedback-loop caused the Sarin Gas Attack in Toyko in '95.
From a foreign perspective, my biggest fear is that assholes in my nation use this as a blueprint and getting emboldened to storm our Parliament.
You're right, it makes the USA look like shit to have the Capitol stormed by raging lunatics, but I wouldn't assume it makes you look unreliable, more torn apart internally... not like that's any better, it's just a different flavour of bad.