In the era of livestreams and corporate events, it had nowhere to go. ReedPop and the ESA could have tried numerous times to get consumer engagement up, by maybe offering demos of what was on the showfloor. But that never happened.
Hopefully smaller events like Gamescom, Paris Games Week, Siegecon, etc take time to look at where E3 failed, and aim to improve engagement with the consumer base. Of which to me, at least, feels a bit aimless due to the sorry state of games released in Generation 8.