I hope they bring back a few of the classics, such as Laser and Plasma Rifles (I know they'll have them according to the teaser, you can see them).
I think- knowing Bethesda- they'll have a lot of nice weapons. Hopefully a nice bit more than New Vegas and 3 if it isn't much to ask for.
Also, with the Institute, who are advanced in technology, Fallout 4 will probably show a wide variety of amazing new energy weapons. If they keep the skill for Energy Weapons (they prob will), it'd likely be very useful.