The R8/HOME could work.. I simply don't trust Rihanna team to make it work. If it was Taylor or Katy I wouldn't be worried the slightest cause I know their teams can make it work but Rihanna's
Also Rihanna is so fickle that by the time its time to start going back on R8 she's going to be over R8 and won't be bothered to revive the era.
They could announce the tour right after her Grammy performance and start touring in August/Sept 2015.