Let's pontificate on the dynamics of "forking":
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Does this sound reasonable?
TLDR: I think the forking dynamics result in an unstable equilibrium such that one chain eventually becomes dominant.
True. I think that could be a scenario.
Nevertheless it would definitely damage the mainstream adoption and market valuations of all cryptocurrencies imo.
You are right when you assume that the valuations will go for chain A and chain B to 50% at first. But also both will loose alot more cause of the overall confusion and trust that was lost to mainstream adopters that werent aware of such things to happen.
If such a incident really occurs and alot of people find themselves in the middle of a nerd-/kiddy-fight with maybe thousands of US-Dollars invested even trust in cryptocurrencies in general will take a HUGE hit. Like beetcoin put it right who gurantees that the next altcoin wont run into such inner-circle-fights again?
It would lead to the insight that cryptocurrencies maybe a good mean to perform value transactions but not a good place to invest wealth.
I see your worry, but I guess I am more optimist about the collective wisdom of our bitcoin community.
If such a fork were credibly on the table, it would be televised in advance across the community. I think in most disputes it would be clear before the first forked-code is downloaded which chain will win. The miners have an incentive to "make the right choice" from the get go, so we would see all sorts of polls and surveys to help them make their decision. Mainstream adopters would just get dragged along with the majority, without any real effort or concern on their part.
In the (extremely?) unlikely event that we do have a ~50/50 forks, again I think this would be predicted in advance. Perhaps people running the web-wallets like Blockchain.info (the wallets the mainstream users use) could simply track the coins on both forks and calculate wallet balance based on the real-time market value of the pre and post fork coins. Again this would be fairly transparent to the mainstream user. Somehow, I think market forces would solve the problem very quickly without causing too much pain to the mainstream user.
