I think it largely depends on who will be found as the culprit.

If it would be found that this is an Islamist terror attack the aftermath will be much more pronounced then a scenario where the blame will be on say some extreme right wing group.

Much of the lose of freedom we all suffer from is due to entrenched xenophobia becoming political agenda, it seems much harder to enact changes when the criminals are white Americans ala Timothy McVeigh or some horrific mass shooting