Peter got back to his home Earth 616 universe sat down and thought about having a look About his universe's Miles Morales.He searched Is there an alternate version of Miles Morales? And what the result came he was shocked by it.
After looking Morales up, all he says is 'Oh my God'. Obviously it was something very surprising.
Like Peter Parker died in Ultimate Universe by the hand of Sinister Six, Miles could have been a victim of a roadside battle between Sinister Six and Spidey. And he died among the general citizen causalities.
If this is the possibility then either internet result could have told about his death or some blog by his parents and friends about "How Spider-Man killed Miles Morales" like the one in Ultimate Fallout Mary Jane wrote about "How SHIELD killed Peter Parker". If this happens Peter will have one more death to blame himself about.
It may be possible that Miles turns out Peter's old classmate who he didn't know. Miles in Ultimate Universe was already a fan of Spider-Man so in 616 universe he may turn out to be a big time Spidey fanboy. Peter comes across his blog in which he keeps each and every record of his with a hidden message that he knows who he really is.
Third Possibility is as a villain. Spider-Man has a big time rogue gallery and its almost impossible to keep track of every villain he defeated's real name and address. What if he turns out to be his regular nemesis or may be a failed clone experiment by Jackal or something like that.
Have heard rumors about Miles replacing Peter Parker after his rumored death in #700 but who knows.