But people are creative, and some other method could be used in the future. The Boston Marathon bombing was only 3 deaths, but 264 injured, and that was just a pressure cooker. The Trollhättan school attack was 3 killed with a sword.
Guns are a tool, a very deadly tool, but a tool none the less. Removing them from the US would be near impossible at this point (with the 2nd and 4th amendments getting in the way). It's also not all that popular in this country. Stricter gun laws don't seem to help (see the Buffalo shooting, in a state with red-flag laws).
One interesting point I heard raised is that the phrase "going postal" was born from an era where workplace shootings became common, but have since near disappeared (with background checks being a large part of the reason). Figuring out why our younger population is doing down the route they have the last 25'ish years is something that has yet to be corrected.