Here is a video showing that it is really not hard to remove the intercooler:
Having said that, all early production 335 water pumps fail. If yours has not failed, you will unlikely get more than 100k out of it. When they fail, the coolant is essentially exchanged during the replacement. BMW told me that the coolant is "lifetime" in my 335 - i.e. the lifetime of my pump, which was about 62 k miles. so, I have a collant flush, hopefully good for the "lifetime" of my new pump (?antoher 62k miles?).