Your cool looking armor is safe, devs have said it won't change.
BUT
Say you have darkleaf breastplate which has AC5. You'll be able to craft it in all the normal ways. This is fine for druids. There is also the standard metal breastplate (breastplate) AC 5 that your druid can't use.
All this is fine until you reach level 8.
In the new system you'll still be able to use your DL breastplate with its normal qualities, but other toons will be able to get metal armors like
Lvl8 battle breastplate AC8, which can also get +6 enhancement
lvl14 magecrafted breastplate AC11, max dex 4,which can go up to +6
lvl20 mountain brestplate AC15, max dex 5, +7 maximum enhancement .
These will be random drops at appropriate level and will be able to be crafted.
Current named items will be updated, so duelists leathers will have values increased, but crafted and random armors already in existence won't get these increases.
So, yes you can keep your good-looking darkleaf breastplate and craft it to +5 to give you Ac10 for your level 20 druid, but another toon wearing a metal breastplate could craft +7 mountain breastplate for AC22.
It seems someone dropped the ball on special (eg darkleaf) non-steel armors so there are no non-metallic armors in their list except leather (they also forgot about mithral which is now inferior to steel), so druids are pretty much stuck with leather armor, despite the fact they have proficiency with medium armor!
Luckily druids aren't an important part of the expansion