We have heard from the festival! It was kind of them to reply so promptly.
And ...
https://twitter.com/VerbierFestival/status/1340989525607272448

It says:
Since the onset of the COVID-19 pandemicearly this year, my Nobuyuki Tsujii news search has yielded mostly concert cancellation notices, from outside Japan. So this morning when this item (image below) turned up, my eyes popped:

Musiciens – Verbier Festival
www.verbierfestival.com › musiciens
23 hours ago — Blythe Teh Engstroem · Yuri Temirkanov · Bryn Terfel · Alexandre Tharaud · Christian Thompson · Daniil Trifonov · Nobuyuki Tsujii · Çiğdem Tunçelli ...
Nobuyuki Tsujii -- to my knowledge -- has never appeared in the Verbier Festival, considered one of the most prestigious music festivals in the world. It is a slight on Nobu that has pained me for a long time. The Verbier is a summer festival held in the Swiss mountains. Frequent participants include the likes of Martha Argerich and Evgeny Kissin. Nobu has a fondness for summer festivals, and I am sure he would especially love to participate in this one.
Needless to say, I clicked on the Musiciens – Verbier Festival link right away. It leads to a page in French, titled "Artistes invités au Verbier Festival" [Artists invited to the Verbier Festival], with names of artists listed in alphabetical order. Under the letter T, who did I see coming after Danill Trifonov? I took a snapshot for record.
Image below: snapshot of part of the "Artistes invités au Verbier Festival" list found at URL https://www.verbierfestival.com/musiciens/
Curiously, Nobu's name is missing on the English side of that page https://www.verbierfestival.com/en/musicians/
Image below: Image of English side of that part of the same list
What gives???
Of course further investigation was in order.
It turns out that on November 5, the festival made an announcement on Twitter and Facebook, as follows:
We are pleased to announce that Verbier Festival will take place from 16 July to 1 August 2021, with musicians and audiences returning to venues across Verbier.
Enhancements have been put in place for the Festival, in consultation with medical professionals, to ensure that the Festival can take place with live concerts.
Further details and the full programme for the Verbier Festival’s 2021 edition will be announced 28 January 2021.
Visit our website for more details: www.verbierfestival.com/en
A press release dated November 10 mentions Valery Gergiev as the festival's Orchestra Music Director.
It seems a reasonable guess that Nobu is among the artists that have been invited to appear in the 2021 festival. Yet, the absence of his name on the English page casts a shadow on that assumption. The omission may be due to an oversight, or something else ...
This is pure speculation on my part. But I suspect that Nobu might have been invited by Mo. Gergiev -- who for many years has taken Nobu under his wings -- to perform with an orchestra. The arrangement may have been somewhat haphazard (as is the wont of ultra-busy Mo. Gergiev ^_^) -- or it may have been tentative -- and the webmaster never got around to adding Nobu's name on the English side.
The 2020 Verbier Festival was cancelled, as with all European festivals. With the pandemic very much still looming large all over the world, it is a valiant move for the festival to announce its return in 2021. I salute the organizers and wish them and the festival the very best. And, honestly, it will make me very happy if Nobu is indeed -- at long last -- on the list of the "Artistes invités au Verbier Festival", as he so deserves.
Fingers crossed. Further investigation pending. Please stay tuned.