This is exactly what I'm saying. Pre-recorded demos are much more likely and would essentially serve the same purpose, they would just save money and resources on getting a live stream up and running.
I work in corporate video production and I can confidently tell you that a big tech company like Nintendo is not spending the money on a big live stream with hosts and sets, without giving people time to plan to watch it. They know this is normally E3 time so they've probably been planning this for months already, without the knowledge that E3 would be canceled. I could see that cancelation being a reason to adjust their plans, for sure.
Anecdotal evidence but I just finished work on a 2-hour project for a global food company, all of those videos within the presentation were pre-recorded (some I filmed myself in the beginning of May), and even still they gave 2 weeks' notice for attendees.
The 24-hour cycle of announcement to debut for Directs is a model they've used for like 9 going on 10 years so it works for them because the audience has been conditioned to expect it. At this point, especially considering the Reddit post was removed, it's safe to say a Direct is happening on the 15th. Not so safe to say a Treehouse is happening alongside it if it doesn't get announced this week. That's all I'm saying.