It fell apart when they revealed who Jacob was. The flash deadways was another horrible mistake.
This is not the end of the franchise. I think there will be a Lost movie, Damon and Carlton even signed up for one when they choose an end date. It will most likely be about when Hurley is is charge of the island and why it sank. There will be lots of books written. Probably as many as there have been for Star Wars that will explain most the things we didn't get answers to. There will also be video games that will do the same.
I'll even go as far as to predict there will be another series sometime in the next ten or so years. Maybe one that will focus on Sun and Jins kid. The show will be about him wanting to find out what happened to his parents.
