User blog comment:Blitz0248/What happened to Infinite?/@comment-1672596-20171113195324

Not sure, since they really don't elaborate on it (and before anyone mentions it, technically, Tails only mentions that the Phantom Ruby was moving underground, not necessarily Infinite, which doesn't really confirm anything since Infinite had the final prototype, not the Phantom Ruby itself embedded into his chest).

For that matter, they hadn't elaborated on what exactly happened to Dr. Eggman after his Death Egg Robot got destroyed, either.