Both will probably be non-existent in a few years. If by some chance Monero survives it will find its use as a privacy-centric currency / store of value, not as an investment vehicle. The non-fixed emission (to maintain mining incentives ad infinitum) means that it will never have the same scarcity as Bitcoin, but I think it's already been demonstrated that scarcity in altcoin distribution is wholly overrated.
Fluffy, what do you mean Monero will probably be non-existent in a few years? What makes you say that?
Lack of consumer adoption will be the downfall of many of the altcoin projects. It's critical to understand the paramount importance of brand name.
There is a fickle nature to the consumer, and picking the winners can be tough. It could be Monero or it could be BananaCoin.
None of these cryptocurrency have any current relevance to any 'consumer' at present, with perhaps BTC having very limited relevance. Any or all of these coins can continue as long as people are interested in them.
At some point there will probably be an event, innovation or discovery that could propel any currency with a good dev team into the stratosphere. What they should not do is let themselves atrophy like the BTC and LTC team have done.
In such an event, 'contender' currencies include NXT, Dash, Bytecoin, Monero, Boolberry and quite a few others - even if Monero devs walked away in a few years there could still be a take over and a chance of mainstream for Monero or any of the others.
I think that, given the strengths and competition (bad tempered and healthy) of Cryptonote dev teams it is likely to be a Cryptonote that takes advantage.
