How Will Gavel Effect Us?

As we all know(or I hope you know) there a big change to items in gavel update.
teaser: 0:32

salted also posted a pic long ago of another item, but the forums got resarted so it's gone ):
How will it (the change) affect our items?
now the items can do different types of damage( fire dmg, neutral dmg...)
and the Id's are also different(Walk speed, Exploding...)
what will happen to the old items?
Are they going to change?
Are they going to stay the same?
Are they going to be useless now? (I dont think it's going to happen :D)
Are all the ID's on then going to be rerolled? and the dmg as well?
(I'm sorry for any Grammer Mistakes, I am not from USA or UK so fill free to correct me)

 

From what I remember, they said that all the current items will be automatically converted to the new system somehow. I wish I could find the post for you, but it got deleted in the great forum wipe.