What if the Internal Revenue service of the US decided to tax bitcoin transactions, what would be the possible effects on its price and the bitcoin community. Will the other governments follow?

The price of bitcoin still uptrend, will it reach $1000 again?

With many new cryptocurrencies sprouting in the net, is it possible that bitcoin can be overtaken as a top digital currency in the future? Is ethereum  or other well known cryptocurrencies can be a threat to bitcoin dominance?