Extra page policy ends at on December 31.
My most treasured expired passport was valid from 1995 to 2005. The reason I like it best is that traveled so often during that decade that I actually had to get extra pages. I beef up the need did by requesting a stamp “as a souvenir” at every passport control opportunity. (I did get close to needing extras in the 2005 to 2015 passport. ) It will also be my only passport with extra pages, because starting on January 1, 2016. Americans will no longer be given the opportunity to add pages to existing passports. I have no idea why.
Bottom line is that if you travel a lot internationally, you might want to apply for extra pages before the end of the year so you won’t have to prematurely renew. After the first of the year, renewing (i.e., getting a whole new passport) is your only option At the time, however, you will be able to choose a 52-page book rather than the standard 28-page passport. FoMoInfo on the new regs.