I'm a bit worried. But maybe its not necessary 

I know if you want to save your own data from Carbonite you need to back up you lua file from the Saved Variables folder.

Is this still possible when WotLK comes out?

With other words can I backup my lua file and put it in the SV folder when the next version (wotlk ready) of Carbo comes out? Or will all things be messed up?

 I was very glad I could import all my notes from Cartographer, and remove Cartographer from my addon folder.
This week I putted the lua file in the SV folder on the PTR and nothing shows on the map.
I know this doesn't mean anything cause Carbo doesn't work properly at all on the PTR.

Will there be an import from the 'old' version of Carbo to the new?

I often read the advise to delete the carbonite. lua file from the SV folder. That means that you loose all of your data. Isn't it possible to 'write' the 'own' data to another file in the SV folder?
Cause now it isn't and I think sometimes its a good thing to delete the lua file I guess, but I will never do that cause of all my notes.

I do not recommend you delete the Carbonite.lua savedvariables file unless you are having major settings problems or the file was corrupted.

1.83 works on the PTR servers. The Carbonite.lua savedvariables format is the same, so when (if) the 3.0.x patch is released next week, it should just work.