In brief: The Steam Game Festival is back, but with a new name that better conveys the event's overall message. The event is scheduled to coincide with the Electronic Entertainment Expo (E3). This year's show is being planned as an online-only event with tentative dates of June 15-17. A list of participants is expected closer to the show date.
Starting June 16 and running through June 22, Valve will host the Steam Next Fest. This multi-day celebration of upcoming games will afford fans the opportunity to try out hundreds of demos and watch livestreams from devs about titles they are currently working on. Viewers will even have the chance to chat with developers and ask questions about their upcoming games.
For devs, it's an opportunity to further build a following for a particular game or franchise and field valuable feedback early enough in the process that changes can be made if deemed necessary.
E3 2020 was called off entirely due to the pandemic, prompting developers and publishers to host their own announcements. It was better than nothing, and a virtual E3 is likely to be better than the fragmented set of streams we got last summer, but a true return to form probably won't happen until 2022 at the very earliest.