Well guys.. If bitcoin dies tomorrow because of such a high rate or any other reason .. Which is the best altcoin will the person switch to first? This means the altcoin in which the population will more likely to invest on??
That's something very unlikely to happen. Some of the reasons you pointed out probably would not be enough to cause such an event. Considering the fact that Bitcoin has increased significantly in value in recent months, the fees are a bit high, in fact, but only in relation to small transactions. For larger amounts, fees are relatively low. Either way, I think this is something that can be adjusted without major complications.
But to answer your question, people would look for something more conservative and similar to Bitcoin, so I think that the currency with greatest potential to replace Bitcoin, in case of a catastrophe, would be Litecoin due to the fair distribution and some improvements. And it looks like they will try to improve anonymity.
Soon after, Monero could be a good one, due to improvements that allow anonymous transactions, and active community, of course.