Yes what you say is true, and bitcoin may become stuck. But we have hard forked before, when has a living entity changed a part of its DNA? It still remains a lot more flexible than the things we normally refer to when talking about evolution. I agree with what you say, I just think you just underestimate the flexibility of software.
A second point I would like to make (sorry if it's been addressed before) is that unless something other than mining comes along as a solution to centralised ledgers, network strength becomes the major imperative. Bitcoin managed to get out of the danger zone because nobody knew or cared what crypto was while it had time to build strength. Now the boat has sailed, any new coin that uses the concept of mining (an alternative to this wouldn't be an alt-coin, it would be a new paradigm all together) will always have trouble getting of the ground.
Anyway, given your dismissive response to my last post I'm going to assume that I'm in a troll thread and probably stop trying to have a pleasant conversation here.
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just to let you know, nem has come up with an exciting novel approach that is vastly different than mining and also PoS. its called proof of importance. its similar to PoS in the way coins are initially distributed(nem had 3000 stake holders - unlike nxt) but from then on its much different.
nodes are reward based on how important they are to the network. it incentives nodes to make transactions with nodes that are also important to the network(like a merchant that does many transactions in and out to many people further distributing the coin) the more important you are to the network ie. the more you support and secure the network, the higher your importance is and therefore the higher the percentage chance of you forging the next block. nodes are punished for trying to game the system by actually getting a lower importance, it does this(i think) by working out how important a particular transaction is based on how important the node is with which you made the transaction. (as far as i know, thats how it works anyway)
its a major break through. and not something to pass by with out thought.
i agree that any new coin will have a hard time building a strong network. but a network that directly rewards those who help support the network and make it larger is a network that should, in theory, grow stronger, very fast. starting out with 3000 original stake holders who all get the same amount also helps with network effect early on.