You make a fair point, I get it and you are right. You'd expect a glimmer of something by now. Maybe with the GR Yaris nobody was expecting is so they wanted to generate interest by letting such things out. Perhaps as you rightly point out interest in the replacement GT86 is so high, that by not showing anything it keeps people guessing and thus interest levels high. It's hard to know but I agree given a launch in a years time you would expect something. It is possible that it could have been delayed and if so I'm sure Toyota would not want to have a similar situation that they did with the Supra, so it is perhaps more likely that nothing is set in stone.
Maybe the pandemic has pushed it back a bit and once things settle down we'll hear about it. It could also be that they want to push the GR Yaris which is getting all the publicity and marketing at the moment, so they will wait till that is over before muddying the waters with the new GT86/GR86. That would make sense. Especially so with the new GR86 being a Gazoo Racing product. This is big news as it is with the Yaris, so one product launch at a tie is the obvious way to play it.