I really doubt New Line would re-release Pleasantville.
The current release is great and probably can't be improved upon much.
At it's current price, you can't go wrong picking this up.
EDIT:
Someone congratulate me... this post just made me a member of the 1000 post club.
I don't see New Line putting out a new edition, after all it is Platinum Series and New Line won't be releasing any catalog titles as infinifilm releases.