So, further to the latest state of the game and the new eternal format discussions, it seems that the contents of the much discussed 'blast from the past' event have actually been out since December 2021 and it's... only standard sets with a long banned list:

https://magic.wizards.com/en/article.../midweek-magic

If this is the new eternal format... well... people that were dreaming of vintage, modern and pioneer on arena will have their hopes brought to reality...