It's been discussed for the last 2 years already it isn't a new development.
e3 has gone almost entirely consumer, news outlets struggle waiting in lines to get good looks at games and appointments are few and far between for many outlets due to the influx of demand. The show is a tourist attraction now, which came to a massive head last year and this year AND now it's about to be cancelled leading to the superior format of personal stage shows and directs. Sony playing music on stage for 40 minutes isn't how I want to consume my news and it appears many others feel the same.
Not to mention the excessive rumors of company's pulling out like Sony already has and MS doesn't even have their show on that campus anymore.
you can put 2 and 2 together easily.
I hear what you're saying, but it is still speculation saying that 'E3 is dead' until we know more. The only valid comment is "E3 2020 is dead". The format of E3 may well change in the future....but I personally do not think the E3 event will die outright