The two money masters go at it.
Short-term, yes it is very possible for alt-chains to live alongside Bitcoin. Indeed LiteCoin already is accepted in a few places alongside BTC.
But long term, money works in such a way that the most widely accepted one tends to win out over the competitors unless there is some other factor preventing this natural process from continuing. In the case of fiat currencies, each nation mandates that its currency is used. If they didn't then the dollar would likely be used worldwide right now.
True, true. But there is something you're missing.
Money network effects are prompted by market access. It's all about market access, and traditionally that has been limited to the physical and the local. You go to the store you need to have what the shopkeeper will value. You travel to a foreign land you need to have what they value.
As you point out dollars would be used worldwide if countries didn't mandate their own currencies, due to the network effect of more and more people accepting dollars. However... dollars
have been advancing their worldwide acceptance. Why? It's because it has become easier for someone, anywhere in the world, to meet with someone that can change dollars into something valuable to them, if dollars are not, and that's thanks to technology. As dollars have become digital it has become easier to transfer them (much harder with physical dollars). The only thing gumming up the works is regulation and an industry not exactly known for leading technical innovation.
Cryptocurrencies are digital by nature, and the Internet is ubiquitous.
That means market access is uniform for users of cryptocurrency. Network effects, normally amplified by geographic practicality, are restructured.
Over time, the alt-coins will become worthless and one main crypto currency will dominate everything (maybe it'll be Bitcoin or something else, but one coin will rule them all).
I disagree.
It's just a matter of network effects... this is why we all use the same email protocol.
It's not the same thing. Email servers are set up to interact and behave a certain way, the email protocol. If you don't follow the protocol you can't access the system. But what is the money protocol? There is no inflexible rule. As long as someone else values something you have the thing can serve as money. The Internet allows for finding others that value what you have to be at a maximum. The digital nature of cryptocurrencies mean moving that value the easiest way possible is also at a maximum. Taken together these factors impact the old paradigm of physical money network effects.
The caveat to this is if there is a niche which Bitcoin cannot fill, then an alt-coin might live there. But this is the exception to the rule that one main coin should come to dominate.
There is a niche that Bitcoin can't fill. It's what led me to start promoting alt-coins in the first place. That niche is that they are
not Bitcoin.
That's something the cryptocurrency market needs for many reasons. The first one
I realized was potential market domination of Bitcoin Foundation. That fear is embodied in recent forum posts even on this day. Another one is the block size issue. If there were only Bitcoin I think there would be far more pressure to "get it right" whatever that means, because there are varied (irreconcilable) opinions. Another is hard fork risk should Bitcoin become so large the voices pulling in different directions must split. Still another is technical risk, for example, if some problem arises with Bitcoin's hashing algorithms (or ASIC hardware monopolizing it) where others like Litecoin use something different, or where Gavin goofed with the version 0.8.0 fork; imagine the economic carnage if Bitcoin were 10 times the acceptance it has now.
Bitcon's future isn't certain. Having alternates exist economically beside it I believe definitely strengthens cryptocurrency overall, and is why they will have co-existing value.