Anyway, here's how I think it will turn out: Based on the first 'fake' summary in December last year, Eggman's plans to use the ancient technology while having secretly stolen that Chaos Emeralds goes haywire when Starfall Island's Titan Robots take over and trap him by unleashing the Cyberspace to lure people in via Sage, who may be a haunted ghost who is trapped due to the terrible civil war that killed virtually everyone and because of her loniness and loss, she lost all sympathy to become the main antagonist, while stealing his memories to begin her plot to put in fake ones and force other people who do not escape the digital realms to stay forever to her own entertainment or whatever other reason.
But perhaps Eggman's consciousness is put into the drone which would help and/or trick Sonic, who barely escapes after he and his friends end up sucked in at the cost of his memories into finding the Chaos Emeralds for his own gains. While finding the Memory Tokens to rescue his friends as well as restore their memories, going through the Cyberspace levels to regain his own as well as his abilities using the Skill Tree, and locating the Chaos Emeralds, Sage, seeing that he escaped and wants to achieve is goal due to his strong spirit and heart, and not wanting history to repeat itself, keeps on telling him to leave but he does.
Once Sonic regains his memories and going through his own emotional turmoil while finding the Chaos Emeralds, by learning of the truth and attempting to rescue his friends including Knuckles who, theoretically, has been kidnapped in the Prologue Short that's coming, and learns that Eggman, who also regains his memories, has tricked him, after fighting against him when the evil scientist attempts to steal everybody's memories and turn them into empty husks to become his slaves, Sage then attacks and angrily kidnaps him as well as Sonic's friends once again and steals the Emeralds by using the negative powers to merge with a giant Titan to destroy him. Either Sonic is killed or imprisoned in the Cyberspace, the cries from his friends renew his spirit and memories before he manages to escape by the Chaos Emeralds hearing his calls, and transforms into Super Sonic to defeat Sage once and for all.
While the first ending theory is still similar to my previous theories that it will lead into the events of Sonic Prime, here's a new ending of how the game would turn out.
Sage returns to normal and Sonic realizes that she has suffered such pain of being all alone after the tragic deaths of her own family, friends and people, and he and his friends sympathize her loss. They then give her support and Knuckles reveals how he went through the similar thing, while Sonic ensures Sage that the War is over, that she can't always live in the past but move forward to the future, even in the afterlife. He reveals that he and his friends have had been alone themselves, but it was destiny that lead them all together as a family.
Ending idea 1: Sage, realizing her mistake, sheds tears before thanking Sonic's group for helping her finally move on and once they promise to never return to Starfall Islands again and to ensure they would not repeat history, she ascends for the heavens to reunite with her loved ones before they too leave for home, and Eggman leaves as well, vowing revenge against Sonic as usual.
Ending idea 2: Sonic offers Sage to join him and the others so that she won't be alone anymore, just as she accepts, the Titans suddenly begin to self-destruct which forces her, in her way to atone for her actions, to send Sonic's group including Eggman off of Starfall Islands and back to Green Hill Zone(the real one) by using the Master Emerald and Chaos Control, sacrificing herself and destroying Starfall Islands as a result, and the heroes mourn for the loss of Sage. In the post-credits scene, Sonic, still in mourning, is greeted with a freed spirit of Sage where he happily embraces her, before she thanks him for his kindness and once he promises to take care of his own friends, she ascends for the heavens to reunite with her late loved ones, finally in peace. The story ends with Sonic, vowing to never forget again, runs off to happily join Tails, Amy and everybody else as he promises himself to never take his friends for granted as well as being excited for future adventures up ahead.
As I said, I'm still convinced that this game will lead into the events of Sonic Prime and it won't have a good ending, this is what I think what the story may happen so far.