Could this be the Missing Link?

A strong frontrunner for the dawning of this technique is 1999's THE MATRIX. Take a look:



Multiple techniques are used.  Flashes to white.  The dip to black is implemented.  But also the hard cut to black, accomplishing a very similar, but more aggressive effect.

Also notice how the last half of the trailer is almost completely devoid dips to black.  As the action picks up in pace, the trailer uses hard cuts bombarding us with images.

The dips to black are largely used for their dreamy effect in the first half of the trailer.

This may very well be the watershed trailer that solidified the default use of dips to black in movie trailers.  But I think we can find earlier examples that may have even influenced this trailer.

In fact, I know we can.  And that'll be my next post.