This will happen to coins which have no solid concept or marketing strategy. I see a lot of people trying to benefit from the popularity of bitcoins by launching their own coins. Some people might invest because of tempting advertisements but these coins will never get mass adoption. More of these coins will keep getting mined without any increase in demand and thus they will finally collapse. However, in case of bitcoins, I see a lot of growth possible. There are a lot of people who have not invested in bitcoins till now but are showing some sort of interest.