Angela Slatter writes a refreshing post about considerations for your new publishing relationship, and on whether it will last forever:
Short answer: No, probably not.
Long answer: Many things can happen in a writer-publisher relationship to make it either go bad or simply reach the natural end of its lifespan
Angela lists a comprehensive set of circumstances that can account for swapping publishers and finishes with:
Try not to burn bridges, no matter how nuts someone seems or how bad their behaviour. If someone asks you about your experience with such and such a publisher (or writer) be professional but honest. Don’t start a flame war or internecine strife – this may be interesting for bystanders, but it doesn’t do your writing community any good.
Read the list of reasons here, they are worth checking out. It's always good to be prepared for possible career events: http://www.angelaslatter.com/will-my-publisher-be-my-publisher-forever/