Say BTC does become the currency that people rely on.  How would a loan system work?  I would imagine people would still need to take out loans for large purchases, such as cars and houses.

Without a credit system how does something like that play out?  Would credit cards in BTC exist, and you still received a credit score that allowed you to take out money for a house?  The fluctuation of the BTC price definitely makes it difficult for that model to work. 

I am all about Bitcoins, but I can't seem to wrap my head around this part of society that exists, and is still required with our current mentality.

Not sure if this is the right location for this, but I figured this would be a good place to start.