Monroville said:

I remember ImpFighter... then he changed his mind again and said they would go back to grey.

Really?, then I guess I missed that.

However, having had a chance to have a closer look at the clip, it seems to me as if the 'Revisited' colour of the standard TIEs actually varies in certain shots of this preview. It looks as if it's the exact shade of blue as the existing SE version in some shots, and slighty less so in others. But there's quite a lean towards a greyer TIE colouring during the shot of the close-up of the 'Executor's underside. To be honest, I kinda like the shade in that particular shot the best, but pause the comparison to see what I mean.

I'm sure adywan will confirm about this either way, when he gets a chance.