Konami’s announced the bulk of events coming for May, along with early June.
Elegant Mai returns in Duel World. Previously she came with Vennu and various Amazoness cards.
A new Duel-a-Thon is coming that gives a chance to unlock a new Legendary Duelist. The Japanese Dialogue seems to vaguely point to this being Syrus Truesdale but specifics beyond that are unknown, so we can’t say for certain.
Arkana comes to the gate. This will be a chance for people to unlock him who didn’t get him in the Battle City Begins event. He specializes in Dark Magician related cards and is the sole source of the useful Anti-Magic Arrows.
A second chance for people to obtain Jesse as an unlockable character along with new card rewards.
Late May will introduce Tristan Taylor to Duel Links to obtain new Reward Cards.
Late May will be the start of the Duel Links World Championship 2018 Duel Links Qualifiers
Early June will include a Duel-a-Thon to earn rewards.
Also Early Junes will be the return of the Tag Duel Tournament, where you can Duel this time with GX characters as your partner.
Unspecified improvements will be added to the Vanguard.