I would put money on it being changed so that they only have to introduce one person rather than a whole new House. The name change... well that seems more arbitrary, but maybe they are planning on using Sansa's girlhood friend, also named Jeyne, in the future? Jeyne Pool does become pretty importan later on. At the very least, Jeyne is a very common name in the series and I see no problem with changing it. Especially if they are getting rid of her background and making her foreign. A more exotic name seems appropriate.