As mentioned above by several posters, any attempt to "re-mine" those coins should be outright rejected. Who will determine what a "lost" coin is? How would you know if my coins are lost or in cold storage? After you re-mine coins then someone shows up and says "I found my coins!", who's coins are now the real coins? Are you going to replace the found coins, and with what coins are you replacing them? And under what authority can you render some coins unusable?
If the 21M cap is ever lifted I would divest at least 50% of my BTC and I would assume the project is now dead. A strict, unchangeable cap is one of the most powerful features of BTC. Without it you basically own benie babies or tulips.
The question I have is if it is completely reasonable for BTC to reach $1 million (and I believe it is), why is the price so low? Banks, institutions, investors, hedge funds, venture capital, etc. should be buying up BTC like there's no tomorrow. I guess they just think it's still too risky? But plenty of businesses are already accepting and using BTC. We are long past proof of concept. The only possible tweaks that still need to occur are in security (exchanges & business, not the network itself) and ease of use.