I like M:tG a lot, but it's a hard none from me. Theros is not only a weird choice, but totally unnecessary (there are a number of Kickstarter 5E Ancient Greece settings, hell Odyssey of the Dragonlords is like, out now, at least to backers. And Ken Hite was coming out with Hellenistika, which I guess he won't bother with now, and which seems like it was a lot cleverer and more daring than Theros seems to be - and I know Odyssey has much better subclass design than Theros does, based on the mentioned subclasses), and taking up resources that could be used for either updating an actual D&D setting, or doing something genuinely new (I really don't mind which). If this sort of muddled thinking is what they're doing with M:tG settings, well, the best thing that could possibly happen is that they stop. And at least reassess what the heck they're doing.
Comparing Hellenistika to Theros or Odyssey of the Dragonlords or Arkadia is a mistake. Theros, Odyssey of the Dragonlords, Arkadia, ect... Are inspired by classical Greece, Homer, and maybe to a degree Hesiod.
Hellenistika is the Hellenistic Era, think more Ptolemies and the other large Greek empires and other nations within their cultural sphere, like Roman, and the Greco-Bactarian state and so on. So it's a lot bigger and more diverse then just classical Greece, so there is no reason for it to negatively impact Hellenistika.
Corona Virus on the other hand might delay it, like it's lead other companies to cancel or delay kickstarters.