Not saying it's impossible as such, but am convinced that we won't see transporters in our lifetimes.
As someome else said earlier, I won't discount it flat-out; no-one knows what the future holds, but I don't beleive that the tech to disassemble and reassemble something as complex as a human body, on a molecular level, will exist in my lifetime, and probably not my children's either.
Personal T6 Ship Wishlist:
Nova/Rhode Island class with Hybrid Pilot BOFF seat.
That is all. (guess this wasn't really a 'list' after all!)
I think transporters are impossible. Converting you to energy just means that the machine is killing you. It's killing you instantaneously and painlessly, but it's still killing you. It then makes a copy of yourself at a new location. Is it really you? Does it contain your soul? I think it's an evil twin.
Wormholes, or Iconian Gates, would be a better alternative to instantaneous travel. These don't tamper with or kill your body when you use them.