Er... they didn't cut the final battle out. They moved it to the Burrow. :)

Harry Potter and the Half-Blood Prince
Feature Trailer
(1:54)

The Burrow is burning in this trailer. Yes, in the book that doesn't happen, but irregardless, it is burning in the trailer. I paused it to verify, and it is definitely the Burrow. Also, WB did a press release, and it was because they wanted to make lots of money that they moved the release date. It.Was.NOT.Because.Of.The.Strike. They were quite clear they wanted to release HP in the same weekend next year as they released Batman this year, in order to attempt to gross the same amount of profit. Pure capitalism. No other reason but greed. Sorry to burst the bubble of empathetic blindness. By the way, I am still seeing the movie opening night at the IMAX. If I don't die of excitement beforehand.

Harry Potter and the Half-Blood Prince
International Teaser Trailer
(1:33)