According to a community post, Blizzard Entertainment has decided to cancel BlizzCon 2020 due to covid-19.
The post, written by Saralyn Smith (Executive Producer at BlizzCon), says the organizers in charge of the event “had many discussions” and explored “different paths we could take.”
“Ultimately, after considering our options, we’ve come to the very difficult decision to not have BlizzCon this year.”
However, an online event is on the horizon. “We’re talking about how we might be able to channel the BlizzCon spirit and connect with you in some way online, far less impacted by the state of health and safety protocols for mass in-person gatherings.”
It may take months though for the online event to happen as this is new territory. “We’d want to do this as soon as we could, but given that this is new-ish territory and the different factors involved, it will most likely be sometime early next year.”
Because esports is also an important part of the event, the organizers are looking for alternatives to bring high-level competition online.

[Sources]: BlizzCon: An Update on BlizzCon – [Archive] and Una actualización sobre BlizzCon – [Archive].