This year's original Free Comic Book Day (FCBD on May 2 was scratched to keep everyone safe during the early onset of the COVID-19 pandemic, and while a rescheduled date is still TBD by the organizers Marvel is breaking with the pack to release its FCBD titles on its own schedule. And yes, they'll still be free to readers (while supplies last).
On July 15, Free Comic Book Day 2020: X-Men will be released - featuring an X of Swords prologue by Jonathan Hickman and artist Pepe Larraz, along with a "second story will also foreshadow an upcoming epic tale by Tom Taylor and Iban Coello." Taylor and Coello have nothing announced in the X-Men line beyond this free story yet, however, this inclusion would infer something bigger from them in "Dawn of X" later in 2020.
X of Swords is an upcoming event - the first X-event in Hickman's run on the franchise - launching in September with X of Swords: Creation. Two more one-shots will follow, then the storyline will cross over into the ongoing X-Men, Excalibur, X-Force, New Mutants, Wolverine, Cable, Hellions, and X-Factor titles, culminating with an as-yet-unnamed one-shot.
And the week after on July 22, Free Comic Book Day 2020: Spider-Man/Venom will be released - with a story by Venom's Donny Cates and Ryan Stegman, and an additional story by Black Cat's Jed MacKay, along with Patrick Gleason.
Earlier this year, Marvel said these stories will be "game changing" for the publisher's line.
Other publishers have not announced when their intended FCBD titles will be released.