Won't ASIC miners eventually break SHA-256 encryption? I might be confused as to how Bitcoin works, but as far as I can tell, ASIC miners are getting better every year and faster at cracking SHA-256 encryption.  Won't this cause the eventual complete obsolescence of SHA-256 encryption entirely, much faster than previously estimated?
Another way to look at it is to take a look at a recent block that was mined, for example, block 388368.  Looking at this block on blockchain.info, you can see that the hash for this block is:

0000000000000000021ff110a589e44f56979254a204557311204f803910fdfa


It took roughly 10 minutes for all of the miners (doing a combined 700,000,000 giga-hashes per second) to find the above hash which has enough leading zeroes (17) to meet the difficulty requirement of the network at that time.  Since the remaining digits after the first 17 leading zeroes could have been anything, there are 16^47 (i.e.16^(64-17)) possible hashes that could have been found which would have satisfied the difficulty requirement (which is 3.92 * 10^56), yet it took all of the mining power of the entire bitcoin network ~10 minutes to find just one hash that met the requirement.  

To crack a hash, you need not just the first 17 digits to match the given hash, but all 64 of the digits to match.  So, extrapolating from the above, it would take 10 * 3.92 * 10^56 minutes to crack a SHA256 hash using all of the mining power of the entire bitcoin network.  That's a long time.