Nike can -- and likely will -- sue under UDRP for ownership of the domain names. In your case, they are almost certain to win, especially considering the current stance of WIPO. Regardless of WIPO pro-corporate rulings so far, take a look at the three points Nike would have to prove:
(i) your domain name is identical or confusingly similar to a trademark or service mark in which the complainant has rights; and
Easy enough...Nike already owns nikeworld.com, which you knew when you registered the names.
(ii) you have no rights or legitimate interests in respect of the domain name; and
Do you have a *legitimate* site there or ready to go there? Can you prove it well beyond the shadow of a doubt? Keep in mind that evidence submitted to WIPO under UDRP has been ignored, especially weak evidence. Putting a Nike news site there will only open you up to copyright infringement suits through US courts even if it *may* protect you from UDRP.
(iii) your domain name has been registered and is being used in bad faith.
You have publicly stated your intention to sell the domain names and profit from them -- the very definition of bad faith, especially according to previous UDRP rulings.
Transferring the names to somebody else will simply change the target of legal actions. Must be a real good friend who is willing to deal with legal problems and fees for you.
~Ladi