1. Nothing
The writers could do absolutely nothing. Towards the end of the fourth season, Finn was being given his own storyline, separate from New York and essentially removed from McKinley. Cory Monteith was in rehab for the final couple of episodes of season four and his character wasnt mentioned at all. Itll be interesting to see if the writers address Finn at all in the first two episodes of season five, which is supposedly a Beatles tribute. It has already been confirmed that Finns death will be addressed in the third episode and that could be it for McKinleys former quarterback. Ive already said that it would be a mistake to try and eradicate all memory of Finn from the show, being the pivotal character he once was. But given how little the writers mentioned characters when they are absent from episodes (Joe and Sugar disappeared without a trace from half of season four), it would not be a massive surprise for Finn not to be mentioned following Cory Monteiths tribute episode.