1.) First off I personally would never buy an extended warranty, which typically only covers issues related to the drive-train, and is NEVER the same as a factory warranty. (Waste of $$ IMO)
2.) You can't predict what's going to happen, no one can tell you what's going to go wrong with YOUR car. It all depends on what happens. 335's are still to early to tell reliability.
....But hey, at least BMW has extended your warranty on HPFP to 10 years or 120K miles. So you don't have that to worry about.