Keanu Reeves won the E3 with his appearance in Cyberpunk 2077, hands down. What many fans might now know is that his character, Johnny Silverhand, may be physically dead and he appears as a cyber ghost that V can see thanks to a chip.
Cyberpunk 2077's latest trailer showed V and Jackie coming out of a heated firefight where the latter was mortally wounded. Dex later wants to see V's chip that is apparently a big deal and when he kills the protagonist, the main man doesn't die but is apparently found by Johnny Silverhand in what seems to be a junkyard.
There is one crucial plot point the trailer didn't show though. The chip that V and Jackie were sent to retrieve is key to immortality but it obviously doesn't protect against bullets and hardware hacking. This part was revealed to journalists behind the closed doors. Instead, it sounds a lot like Soulkiller, a program that would make a digital copy of a Netrunner's mind.
It was made by Alt Cunningham, Johnny's girlfriend, who was later abducted by Saburo Arasaka. He developed his own version that would fry the Netrunner's mind and used it on Alt but her digital "ghost" broke free into the Net. Johnny was later killed while infiltrating Arasaka with Morgan Blackhand but his body was never found.
Considering his ties with Alt, it is not impossible he had access to Soulkiller himself that allowed his digital ghost to escape the impending doom.
This essentially made him immortal, which springs theories about V having access to the same technology since he/ she was implanted with the immortality chip. It could also be the reason why Johnny decided to contact the protagonist.
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Keep in mind this is mostly just speculation at this point but Keanu Reeves' rockstar character is confirmed to be a digital ghost, rather than an actual human being. Furthermore, when creating a character, you can choose a childhood hero between three out of four characters integral to this story. We are all getting Keanu as our hero, aren't we?