None of our current armor will be converted to Armor 2.0, nor will 2.0 versions be able to be pulled from Collections. However, you will be given a 2.0 version of the Majestic Solstice set if you earned it, and all armor in the game will have a 2.0 version that you can grind for again with some exceptions like Trials and Faction gear, since those are still on indefinite hiatus.
Essentially meaning that the conversion to 750 light is actually level 0 and that all of our current equipment may as well be white gear without the new stats. I'm glad to see that they'll allow us to keep our Majestic set not having to earn that twice
The old Armour won't be irrelevant right away as we have to unlock/buy/RNG armour 2.0 perks like 'enhanced hand cannon loader'. It will be quite some time before people will be able to spec their new armour 2.0 sets exactly the way they want for their play style. [spoiler]I expect some PvP players will never get rid of their year 2 sets[/spoiler]
[spoiler]also you will have to reaccquire your exotic armour pieces. You will be able to pull fix roll 2.0 sets from collections but they might not be the Int/Dis/Strength that you want[/spoiler]