I believe the smaller companies are the ones that tend to benefit from the big conferences, because it gives them a chance to talk to people all over the world who might not otherwise be available. Speaking for myself, these cancellations are understandable, but a big problem for my work.
Assuming both intend to ship for sales Christmas 2020, towards september/october of this year we're going to see a heavy marketing push with video trailers for the games they will launch with. Very similar to how Halo 3 was promoted with the launch of the Xbox 360.
E3 2019 might have well been the last one.
I was always curious why it matters at all.
As a consumer you have to wait ages and as a journalist you are there a day earlier or have invites.
It's much cheaper to invite all relevant journalist on a global scale.
But honestly? If I'm able to watch the release show from companies like Ms Sony and co live on YouTube I will do that.
I assume this creates more then enough buzz already.