In five years? Almost none of them. It's not even certain Bitcoin will survive that long, although I believe it will.
Namecoin, despite having a great idea, will not survive since almost no one is implementing the original alt-DNS goal. It almost died after 2 years of abandonment, was somewhat resurrected, but not enough. I have a tiny amount of NMC in an unoffical Mac client that hasn't been updated in a year. If it weren't for BTC-E and merged mining, it would have died already.
I kind of like Doge, but for both practical and political reasons, I don't think it will be around.
Addressing @soniq, I believe the successor(s) to Bitshares BTS may survive, but certainly not PTS itself, they want to get rid of that legacy blockchain as soon as possible.
I would give Litecoin a better chance, partly because it is being used for actual trade, at least to some extent, and will likely hold a nostalgia value for many. Feathercoin I would give less of a chance, but I wouldn't completely count it out.
However, I think the number of alternative tokens will expand greatly, but almost all will not use their own blockchains. They will use things like Counterparty and Ethereum (I don't think Mastercoin will survive that long), and perhaps the platform launched by Bitshares. Sidechains, treechains, etc, could potentially change everything, or might just become forgotten ideas.
Anyway, that's just my briefly considered opinion. I could be completely wrong.
