If they kill Luke off in a lame way it will be as bad as the book the EU originally intended to do the same by Traviss. Was vetoed so they killed off his wife instead. Nothing would prevent me from returning to see the sequels more than Luke going dark or being killed.
If Luke's a lame creepy hermit with no wife or girlfriend, has no children i will also be less than thrilled . He would have been turned into a prequel jedi.