The only coin that we know is going to go up during that time frame is bitcoin and no other, just look at what it is happening now in the market, altcoins went up in value against fiat but most altcoins have been crashing against bitcoin, this particular bull run has been unique, it seems that many investors have lost their faith in altcoins and if that is the case it is going to be even more difficult to predict which altcoin will go in value during the next 3 years.