Best answer by Paul Deschamps
Nobody will know until it happens so you'll just have to keep checking the webstore or Koodo's Facebook Page which is where they announce new device selection.
That said I personally wouldn't expect it as this is the first time Koodo has ever even offered a larger storage size for an iPhone and most are just happy they at least have that option. However if Koodo was to see a mass amount of ppl asking for it then they will do their best to offer it, I personally would love to see it (an iPhone isn't an iPhone without a white front panel to me) as well as any color of the iPhone 6s Plus in 64gb offered by Koodo but I'm not holding my breath.
Remember you can always buy the phone unlocked from Apple or any 3rd party retailer and bring it to Koodo to use on their network.