Al the problems you point out are temporary growing pains. I am not worried of one of them, all these issues forces the market to come up with solutions and that will finally make BTC even stronger. Everyone is complaining about BTC, but look what this experiment has accomplished already! I think people like to complain about BTC to pump an altcoin where they are invested in or have the power over.
Agreed. People talk about other crypto projects taking over but none are as battle tested as bitcoin. It's all good in theory to say Ether is superior, however it has its' only scaling problems to deal with and has yet to have the same pressure on the network as BTC did during Dec/Jan.
The good thing is while BTC is trading sideways Segwit and Lightning Networking are growing in adoption, thus the network will be better prepared to handle the next spike in transactions.