The only altcoin I have any faith in at this time are Litecoins. Litecoins ARE a necessary diversification away from BTC should something bad happen to SHA256 and whatnot 
I think everyone here would agree with me in that it's never wise to put all of your eggs in one (BTC) basket.
I think everyone here would agree with me in that it's never wise to put all of your eggs in one (BTC) basket.
What's SHA256?
It's the encryption algorithm that is used to mine bitcoins. Litecoins on the other hand use scrypt algorithm during mining.
For a super sciencey answer try:
https://en.wikipedia.org/wiki/SHA-2