Since the BTC rewards and fees are now worthless, most miners stop mining BTC and keep mining GNC only. Only a few persist, for sentimental reasons. The BTC block rate drops to near zero for months, until the difficulty gets readjusted.
Then someone, not connected to Blockstream, GNC, or any other bitcoin entity, creates a new altcoin SuperShibaCoin (SSC)....
(Summary of what JorgeSolfi is saying: if one alt-coin overtakes bitcoin, people will lose confidence in cryptocurrency because it will probably happen again, and a series of popping bubbles is not a good store of value).
Yeah thats one of the reasons I am not keen on alt-coins. If an alt-coin took over bitcoin it might be the end of artificial scarcity (aka cryptocurrencies) in general, is my assertion too. You might enjoy this post:
https://bitcointalk.org/index.php?topic=911339.msg10012730or the short tldr; twitter version:
https://twitter.com/adam3us/status/550841397927235584Summary: doesn't merged mining provide a path for an altcoin to steal bitcoin's network power and market cap, with little investment, even without any change to the BTC protocol and without any special mechanism to "transfer" BTC to it?
Could some sidechains innovation provide suitable incentives to miners that would prevent this risk?
I think its quite hard to prevent merge mining automatically because people can steganographically watermark bitcoin tx. eg they could make a multisig where the second sig is not a pub key but a hash of their chain.
However miners could try to find them and block them via whack-a-mole as all users on that network need to know the decoding trick for the stego. As chains dont tend to be secret society things, that could actually work somewhat. You saw some miners and pools blocking unnecessarily bloated clumsy MasterCoin & CounterParty transaction encodings using that kind of approach. (I guess it worked as I think I saw someone say MC & CP now use less clumsy encodings).
Its a little risky to play steganography arms race though because they could bypass that (at the limit steganography wins) by replacing broadcast by sending one hash encoded for each coin public key in the network and bloat the chain even more, and that couldnt be blocked. (Because it would take the respective private key to decode and distinguish from real transaction and thats known only to the affected user).
There is a cleverer to get public steganography through the miner-filter, I wont elaborate as I dont want to give the "meta-coin" and "censor resistant IM" spammers ideas. If you see how too ssshh! (Censor resistant IM like
http://www.reddit.com/r/Bitcoin/comments/2q1gnn/tweetbitorg_censorship_free_content/).
Adam