http://www.kyoto-np.co.jp/top/article/20161208000019 Seems like government is going to push for the 1+5 route
Some on 2ch suggest that JR can build 1 first, and by the time it is completed, free gauge train should be ready for use in the Kyoto-Osaka segment, which will save the country 100B Yen.
Others have suggested that maybe the final segment toward Osaka can be shared with Linear shinkansen to split and save some cost