I believe BTC and LTC and Doge will all be irrelevant by then and we will choose the technically best coin.
But as far as currencies to be remembered.
BTC - it started it all
LTC - it came in second and stayed there till bombing, at which point Doge became a weak second place.
Doge - joke coin, brought many into crypto. Looked strong, lacked business adoption. Educated users on cryptos.
QRK - will be remembered as a CPU-mined coin. and the fastest coin. may struggle in gaining a footing in the market like many other coins.
Honestly, I believe a government (or possibly just some legitimate institution) is gonna put out a P2P crypto coin (that's CPU-mined like QRK or fairquark or any 6-encryption coin) that dominates. ^^Those 4 will be remembered as paving the way and have short term/medium term growth potential. Not long term.
Governments will just have a digital version based on the current currency. There is no way they can totally switch to fully digital in the next 3 years.
You will see the option to pay in digital dollars, physical dollars, or credit cards based on physical dollars.
A government can't reeducate its people on monetary systems, they can only create an alternative based on the current model.
Bitcoin will not vanish in 3 years, i think its just the beginning as governments begin to truly fail.
http://business.financialpost.com/2013/09/19/canadian-mint-pushes-ahead-in-murky-world-of-crypto-currency-with-mintchip-project/ is what I'm thinking of with a P2P currency. Economics professors in the US are advocating that the US gov't gets into cryptos (although I realize that is incredibly improbable), I see that as the only way to create the dominant crypto.
Also, people posting shit like EAC are idiots. I just looked that coin up, because I thought it might be some environmental coin (which would be a nice trait), but its just a block reward schedule based on the earth's rotation.. Honestly?
I agree more so with @Netnox. I diversify my portfolio based on coin families (since this generally creates unique traits in the coins), so CPU-mined, GPU-mined, and BTC are the big 3. I also think that one family will run away with the crypto-king title. We'll have to see who gains momentum later on this year.