Out of curiosity, will aiming be by laser or reticle?

Probably optional.

The first trailer showed a red dot laser sight, but the new HUD utilizes a standard reticule.

As Dark_Chris said, it could be optional, or they simply could have changed it from the first trailer.

If we do get to use a laser sight, I hope we can change the color of it like we could in Revelations. Such a superfluous feature, but it was actually something I had been wanting since RE4, and I was glad we could finally do it in Rev.

Wow, that option must have completely escaped me when playing Revelations; now I'm going to have to boot it up and take a look at it. To me though, red is a more attractive color, so even with the choice to change it, I'd probably just stick with the base.

Every weapon shown so far in both trailers have laser sights. I think it would be pointless having them if you can't use them.