I'm not liquidating my retirement fund in favor of bit coin just yet, but as my purchasing power shrinks over time it might be something worth thinking about. It is just too new to put all of my eggs into one basket just yet.
You never want to put all your eggs in the same basket anyway. Diversifying is not just a healthy strategy, it should be obligatory.
Bitcoin has many advantages, but as I see it most of them are at the same time disadvantages too.
Less red tape? Less protection (such as it is) from the state too.
You can "invest" in "assets" directly and cut the middle man? Yes, but that broker or fund manager does or should actually do a lot of checking beforehand and is more educated in financial matters than 80-90% of people out there.
Etc.
My point being bitcoin is a world changer, and I see it as the precursor to a really neat online contract system, as well as a fast internet payment system (pay for digital goods or services quickly) or even a means to move a lot of value very quickly from one place to the other.
But replacing money? Being better than a state approved pension system? Not likely.