Thankfully there's still the swathes of other comic, video game, and anime conventions out there to get your dose.
ETA: have we all forgotten about San Diego Comic-Con? The literal largest comic convention in the world that most big production companies use as a major event to announce upcoming projects?
E3 taught me a lot about how to sneak into paid conventions and invite-only after parties. Had just moved to LA and a new friend brought me along and taught me the ways.
Yeah, he invited me there, said he got me a ticket. What he actually had for me was a toolbelt, high biz vest and a hardhat. He used to work as an electrician for these events. So we walk in and store our things. In the evening the big publishers would hold private parties. We did the same routine to get into Sony's. It was the mid 2000s and we ended up doing this for multiple events before disbanding :)