Well-known industry journalist and podcaster Jeff Grubb recently revealed that Microsoft's presentation during this year's E3 (which will be an online event) will take place on June 13. The post also features a list of entities that will participate in the fair. It looks like we will see games from publishers such as Square Enix, Bandai Namco, Sega, Gearbox, Nintendo, Capcom, Take-Two Interactive (TTWO), WB and Koch Media.
It's worth noting that the information is not confirmed (although it seems plausible), so for now it should be treated as a rumor.
- Xbox - official website