No, she can't be a Horcrux. But there may be "possession" hooks left in there for Tom to use.

After all, as Swythyv put it; here the revenant is, almost solid, even able to pick up Harry's wand and keep it from him, steadily drawing Ginny's life force from her and getting stronger all the while.

Then Harry sticks a fang through the book and desrtoys its function as a Horcrux and all that life force gets sucked right back into Ginny. Oops?

After all, we know where it's been...