Bitcoin is already in more trouble than people for some reason are admitting. Bitcoin Cash is the most damaging attack on Bitcoin to date, and people simply are not acknowledging that fact (most Bitcoiners anyway). Adam Back says on Twitter, Segwit2x "may" subject the 5k Bitcoin price to "cancellation" if enacted. What makes no sense to some of us is why BCH does not do this already. In fact I think it will unless it is completely and permanently defeated. Right now Bitcoin's mining power is split and chasing 42 million bitcoins! This is a complete violation of Bitcoin's core value proposition, that the hash power will protect strict monetary policy. It has failed to do that. I bought my first bitcoins coming into the MtGox bubble in November 2013, at bubble prices. I lost those in MtGox bankruptcy and bought more. I remained faithful to Bitcoin through all of 2014, 2015, 2016 and most of this year. But I finally gave in and sold at 2700 before the BCH fork. I've missed out on BCH, and giant BTC price gains since I sold. But damn. Strict monetary policy is just gone. I don't know if or when I will ever buy what crypto again. I love what they can do. But Bitcoin... ye had one job. And you blew it! I think there's a fair chance the total BTC/BCH price will fall back through my sell level again. Not sure I will want it, though.

Testnet can be overcome pretty easily with a single ASIC according to Greg Maxwell.