what are the chances of the original Valentine returning?
Not very. Sol destroyed her.
She was out of control, so he had no choice.
It’s been suggested though, that Ramlethal and Elphelt share what is “left” of her memories when they inherited the Prime Field information she absorbed from Sin Kiske... though to what extent that’s true is uncertain.
Elphelt in particular, since she has the power to teleport herself to any Gear containing the Prime Field’s information... which just so happened to be how she met Ky Kiske at first.
Still, it’s a little different from Elphelt’s memories and experiences... more along the lines of “shared information” rather than an emotional traumatic experience.
The reason being, the “other side of Elphelt” (her Darkside) that was programmed to keep Sol from interfering with Justice’ revival, had no understanding of the difference between ‘herself’ and ‘her (real) self’.
Unlike her predecessor, Elphelt couldn’t disobey orders, so her identity was forced to separate from what functioned as her ego or “self”. Hence the split in personality she originally had.
Even so, that information from the first Valentine’s defeat served as the basis for what created Elphelt and Ramlethal... it’s the reason they were created.
Jack-O’ states that she knows Elphelt’s and Ramlethal’s “vulnerabilities” since they are all technically “copies of Aria”... though that’s more of a template comparison.
Every Valentine has different potentials for emotions and personality, and they all have different experiences since they are all based on Humans. That’s what makes each unique, as Bedman explained to Ramlethal.
That’s also why Happy Chaos Valentine is different from the other Valentines and Aria as well... she is her own identity now.