Unsurprisingly, we've had total radio silence since Other M. But it's been almost four years, and STILL NOTHING. Heck, you could say it's been seven years since the last Metroid game worth playing. The gap between Super and Prime? Eight years.
So clearly they know Other M has gone over like a fart in a church, and people want so little with it they probably decided to let the storm pass before doing anything else with it - or at least announcing it to the public. (Yet at the same time they don't have any issues acknowledging it in SSB4.) But if you told me back then that by March 2014 there still wouldn't have been word of anything, I would've called you crazy.
So, prediction time. How long until we get to play a new Metroid game? (Release, not announcement, just to be clear). I'm going to take a shot in the dark and say the second half of 2016. Winner doesn't win anything but bragging rights, mind you. That is, if they even remember they made that prediction to start with.
(And just to make this clear, Retro producers confirmed in an interview many years ago that this was purely a coincidence that got the HOENN CONFIRMED treatment by fans. Especially considering "nearing completion" usually means release within seven years.)