-) Bitcoin mining is an ecological disaster
-) No incentive for nodes to relay transactions once the block subsidy has demised.
-) There are Governments who actually do ban Bitcoin itself.
One about the fundamentals of life on earth, one about the fundamentals of the protocol and one about the fundamentals of society.
1. Technology will improve, chips will become more efficient, driven by the next run up and all the free money to be made
2. Transaction fees
3. State gambling laws. Drugs. Prohibition. Digital "Piracy". Human desires trump law every time.
Your examples are certainly friction, but none of them are showstoppers (imho).
1. Chips becoming more efficient doesn't solve the problem. As long as Bitcoin has the risk of a 50+% attack the dollars to get 50% is the level of security. Not the hash rate. With Bitcoin rising in price mining will cost more and more. With 1000x the market cap of today it is likely that mining will consume 1000x more dollars. I think Bitcoin can only solve this with new features to complicate a 50%+ attack.
2. Sure. But this could make transactions very costly. But there are ways to reduce the relay cost of a transaction...
3. If Bitcoin gets banned, this is not good. But I don't think this will happen in the capitalist counrties...