Do you think Diet Coke could have been repositioned to change consumers’ perceptions of it enough to be considered a drink equally appealing to...

I would argue that Diet Coke could not reposition itself. 
It has been around for too long and its image in the eyes of the public is relatively
set.

Men have been shown to be hostile to the idea of diet
soda in general.  They believe that diet drinks are for women, not for men.  Because of
this, any drink with the word "diet" in its name would surely have a very hard time
appealing to men.  In addition, it is very difficult to remake a product's image.  Diet
Coke has been in existence for almost 30 years.  This means that its image has had time
to set firmly in the American consciousness.

Because of the
presence of the word "diet" in Diet Coke's name, and because Diet Coke had been around
for so long, I do not believe that it could have repositioned
itself.