The bigger thing is this. Smartphones and tablets are HUGE in popularity, but still only a minority of the population have them. Part of that is the cost keeping consumers away but also it is the tech itself. Older (40+) still don't quite "get" it. As time goes by, more and more people will be introduced to the "wonders" of a smart phone and move towards them. As that happens, market share will increase and prices will fall. Only 3-4 years ago you had to pay $1000 for a laptop that today would cost you 500.
As marketshare increases, prices will drop. It really comes down to supply and demand.
I would say that in 5 years the most you are going to pay for a Phone is $400 for top of the line on release day.
PS: I am speaking a bit from recent experience on this. I am "training" my Wife and her Parents on the wonders of smartphones. They all want one, but need their hand held a bit until the training wheels come off. Conversely, my 13 year old son had no fear and has his phone setup better than I do (well he doesnt flash his all the time like me, but his is smooth)
EDIT: I looked up some numbers. Last September 17% of adults had a smartphone, this year it looks like the number is around 40% so my 5 year estimation may be too conservative. More like 2-3 until a solid majority has them