Yes, it is real and I am crying.
The original game was first released in Japan in 2007. The new game comes over 13 years later. Ever since the anime got announced earlier his year, people had hope a sequel was coming, but the announcement was just officially made this week.
There isn't much information regarding a cameo of characters from the original game, other than the two that already appeared on the trailer: Sho Minamimoto (this time as a playable character), and Koki Kariya. The blonde lady who appears in the Remixes (aka the mobile and Switch ports) will also have an appearance and her name is revealed in the trailer as Tsugumi Matsunae.
Is it actually a sequel, though? According to designer Tetsuya Nomura (and google translator), it kind of is! "There is no official Twitter for the game, so I'll bother you. The game that will be the sequel to the anime that will be aired in April next year will be next summer. When I designed the sequel hero, I didn't think that the mask would become a normal world. The mysterious smartphone symbol meant NEO. I look forward to working with you next year. Have a nice year @ Nomura".
Source: Tweet 1
// Tweet 2
// Tweet 3