We just don't have the technology to do so. The amount of time and power required to brute force this is hard to say. It would take who knows how many years it could be after most of us are dead.
Maybe if a future far far away... but not going to happen anytime soon.
I heard some scientists saying that it still may be impossible in the futute because computers will have a limit on how fast they can process information, since information itself cant travel faster than light
Holy crap, the amount of misinformation in this thread is mind boggling.
First off, the theoretical limitation IIRC is because of thermodynamics NOT the speed of light. Everything you do (including calculations) requires energy. There is a minimum amount of energy required for any single calculation and hence you require incredible amounts of energy to actually bruteforce the entire keyspace.

This isn't entirely true as the security of Bitcoin depends on SHA-256, RIPEMD-160 and ECDSA being secure - but bruteforce attacks are not viable.