In the bigger picture - assassinations of individual politicians almost never change the underlying system. The cited late 1800's period of increased political assassinations in the USA didn't significantly change our underlying plutocracy/oligarchy. Whether one hates Trump or loves Trump or is Trump, he is by no means as special as one imagines. Were he to die of natural causes (or anything else) tomorrow, another suitable person would be thrust forward to take his place in the existing system.