But we are not sure whether bitcoins will survive so long as gold has, and that is the reason people are not that comfortable in investing in bitcoins, as it doesn't provides guarantee that it would survive for next 20 years or so as there would be many other currencies entering into the market in the future.
No dear, What you are saying is not absolutely correct. How can you be very sure that bitcoin will keep on growing in future? Future is unpredictable, and there might come a day when bitcoin simply gets disappeared, whereas Gold cannot be disappeared, as Gold is more older then bitcoins.