I think a full-on holiday version of World of Color is definitely something DLR could do in the future. In fact, I think when WoC first began it was said that the whole show is already set up/rigged to where it can easily be changed to a holiday theme and then changed back to 'regular' WoC. But given the current state of DCA, I can't see that DLR would do a full holiday WoC until at least 2012, if not later. TDA/DLR would most likely want to wait until all of the construction is finished and the crowds are rolling in, and then start adding things to the holiday roster of events.
A brief holiday segment of WoC (like the one for 4th of July) seems quite reasonable to me. Whether or not it would be this year is anyone's guess.
Supposedly - according to one of Al Lutz's articles regarding the July 4th WoC segment - TDA was a little apprehensive about committing to a full Halloween version of WoC because they were not sure how it would be received by the public (I am paraphrasing). They wanted to test the waters with the 4th of July WoC segment and see what the feedback was like before forging ahead with a Halloween version. A Halloween segment was a possibility, however.
But...now we are smack dab in the middle of the Halloween Time season at DLR and, so far, no Halloween segment of WoC. What I am wondering/thinking is whether TDA/DLR might decide to do their Halloween segment over Halloween weekend - in other words, not for the whole season, but just on the weekend leading up to Halloween and on Halloween night??

I could see something like that happening. The 4th of July segment just ran for a couple of days, didn't it?
Christmas falls on a weekend this year, so if they were going to do a special holiday segment of WoC, maybe they would do it on that weekend and not for the whole season??