Burst does not define assassins
Many people are complaining about the lackluster burst on the assassin reworks. However, an assassin should not be defined by their burst potential. Mages, in my opinion, are meant to have higher burst than assassins. Assassins should be defined by their ability to get to and kill high priority targets by outsmarting and outmaneuvering them and then get out of the sticky situation they've put themselves in provided that they completed their job correctly. To me, the fantasy of an assassin is one who is a constant threat to vulnerable players on the map due to an ability to find unique ways to get to their target and a variety of tools to outmaneuver them. Most of the assassin reworks accomplish this! Talon has his wall hop, Katarina her shunpo and blades, Leblanc her blink and unique ultimate to trick players on the map. Rengar is a bit of an exception due to a fantasy of a master hunter rather than a strict assassin. In short, high burst potential is something that assassins want, but aren't defined by. Them having less burst than mages is not an issue because they have more unique ways to reliably get to and attack their target.
I do very much understand the issue of late game ADC's potentially being able to auto attack assassins to death before they can get to them, especially for Leblanc because her burst window is the longest. I think that each assassin can work around this, with either fast enough burst or in Leblanc's case clever use of her ultimate and mobility but it that doesn't mean I think its in a balanced place.
I congratulate Riot on their work in the assassin update. I never was an assassin player but I'm very excited to try them out now!