I think top 3 is more realistic. certainly she can pull back into the top 5.
the thing is, I don't think that Jen really liked being #1. She seems to me to really relish the underdog role, rather than the front runner. I think she was still hungry when she was #1, but the expectations were too much. I think she's looser without the #1 ranknig and that helps her game.
she needs to get that serve more consistent...I feel like it lets her down too often.
at this point, though, I can't see anything that Jen does that Serena and Venus don't do better. so top 3 is more realistic than #1.