I've had pseudo for as long as I can remember. I won't sugarcoat it, b/c it is a nasty bug, but it is absolutely not the end of the world. I agree with everyone here that with all the new drugs your son has a good chance of getting rid of this bug, at least for now, but just in case, I think it's only fair that you know that MOST people with CF live with this bug. Pseudo didn't prevent me from having a very normal childhood filled with friends and school and all sorts of activities, from going to away to college and living in a dorm and doing all the "normal" college things, or from going to law school after that. It complicates things, sure, but it also becomes part of the new "normal." And just as your son will learn to deal with the mask on his face for nebs eventually, so he will also learn to deal with occasional lung infections. They are by NO MEANS a death sentence or a sign that his life with CF will be all about pain and the hospital.
Absolutely believe in the power of the drugs and your doctors to get rid of this bug - it could definitely happen. On the other hand, also trust in yourself, your son, and your family to get through whatever curve balls CF throws at you. Take each day at a time and know that most of the time, even the scariest parts of life with CF aren't the end of the world.
Good luck! I'll be sending lots of love and light out to you and your precious little guy!