It's about as -blam!-ing logical as the mathematic equation of 2 + triangle = Lobster The gaping hole in your argument is that no one has actually confirmed any of this, now it's fair to assume that the bit about doing away with light is accurate, but it is no way logical to assume that they will make everyone reset their progress and start back at lvl 20. Suddenly people are no longer about to do VoG, Crota or PoE as they have been, not even bungievision is that stupid. They already admitted they screwed the pooch when they reset people exotics in TDB and vowed never to repeat that mistake. No it is far more likely they will just place characters at a level with suitable xp to ensure their levels match as they are currently.