The weapons in “Ghost in the Shell” are shown as items to help illustrate the 2029 setting. As such, although they loosely follow projections based on current technology, they’re not strictly bound to them – instead being designed based on what will look good in a movie context.
For example, the guns are generally made of metal rather than plastics, and that’s one place where you can see the director and the rest of the staff (although if we’re honest, mostly the director) impressing their own ideas upon the designs. However, on the other hand, it could be that there has been progress in numerically-controlled 3-dimensional metal milling technology and improvements in alloy technology, and what we’re seeing in these weapons is the effect of those improvements and such predictable trends as greater precision in gunsmithing, coupled with lower costs.
In that sense, it would be a mistake to say that the weaponry shown in “Ghost in the Shell” is always futuristic. This is something that both Mamoru Oshii (director) and Noutomi-san (weaponry concept design) have touched upon in their comments.
However, first and foremost, is the desire to design something futuristic the best way to achieve a futuristic design? This is something that many films and works in other genres have failed in. In fact, it woudn’t be far off to say that the concept of “a futuristic design” stopped having real meaning back in the 50s. We believe the movie that really demonstrated that once and for all was “Blade Runner.” But despite all that, since we’ve never actually tried our hand at purely “futuristic designs,” we’ll have to put this down as an open question with no definite answer yet.