I happened upon something interesting while checking out Patrick Fabian's (Howard) Wikipedia page. It turns out he was on the show The Cleaner for one episode, entitled "Rebecca". Here is the first bit in the plot synopsis for that episode:
Here's the full link:
So is this just a crazy coincidence (name of character/title of episode/pianist/meth), or can we make a prediction of what will come of her character? Rebecca, in the brief scenes we've seen her, doesn't seem like a strong happy individual. Something is missing from her humorless life with Chuck, so perhaps it's possible she will develop a little drug problem in upcoming flashbacks. I know I'm stretching here, but crazier things have happened! And it could work as a catalyst for her death / Chuck developing his psychosis. Further, if Chuck were to discover towards the end of this series run, that Jimmy-turning-Saul is getting involved in money laundering for drugs, it would drive a permanent wedge between them, in the leadup to the Breaking Bad era.