Markus

I think I know who it is..

But first I have to explain something: I am sure that Lucia family name is Cortez. She is the daughter of Mercedes Cortez, who would be 56-57 now.

We see a faded billboard of her in GTA 5, one of the very very few characters that appear in later games. We also know from phone calls / messages from her father to Tony, that she wanted to become an actor, but another message from Kent Paul that she seems to be an escord in Little Havana.

Lucia coming from a troubled family would be very fitting.

Jason on the other hand, has some italian look on him, and also the rumors about his voice actor are to have a little american-italian accent.

To keep it short: It is Jason Vercetti and Lucia Cortez.

Third character might be someone from Vice City. Tony is about 70 now, so I am not so sure about it, but I am sure we will get a suprise from the past!