Re: What happens if an algorithm used by Bitcoin becomes obsolete?
I'm not necessarily talking about including this "new replacement code" in the Bitcoin code, but at least having the code on hand, ready to replace the current code. What do you think?
If you have a code in hand to replace the current code, then what's the point of trusting the current code in the first place? 
I believe we would have a hard fork if a flaw was discovered and didn't course complete damage to the Bitcoin network. The world of technology keeps changing over the years.
You have a point but he also has a point to. If all of a sudden, some exploit is found, how long will it take to create something different so that the Bitcoin network remains secure? And what can happen in the meantime? Some time ago I read somewhere that there are already quite some efforts to fight Quantum Computing in terms of encryption algos, but not sure they can easily be applied to Bitcoin in matter of days. Even days can be too much time! I think this is a valid concern!