Listening to the news reports, it seems to me that the hotel ballroom where an assassin tried to kill Trump had some of the same security concerns the Secrets Service had for the Trade Mart where JFK was headed when he was assassinated. A large venue with many entrances that would need to be secured. The Secret Service eventually decided they could secure the Trade Mart, but it wasn't ideal.
When Trump's ballroom is finished, that will greatly enhance presidential security for large events. I hope Trump survives until then.