The economy of the game is being simplified. Things like Vanguard and Crucible commendations are going away and you will no longer need them to buy vendor gear. All you will need is Glimmer. Any Commendations that you currently have can be cashed in for 250 experience points into its respective category.
Has some of this stuff not gone live yet? Because this thing specifically isn't happening for me. I still have to use Marks to buy stuff from Shaxx.
Sorry, there was a mistake in the original wording of the post. You will still need Marks to buy gear, not Glimmer. The simplification comes from the removal of the Commendations as a currency.