A) Buy crypto-related merchandise
B) I would say Justin Sun and Vitalik Buterin ... Justin Sun because he is the Donald Trump of cryptos... Business man trying to conquer something that is essentially anti-business. Vitalik Buterin, because he is the man behind Ethereum... Everything that has followed has been an improvement from Bitcoin and its shortcomings.
C) I would say Proof-of-Work and mining will not exist anymore as virus scanner and browser developers are already blocking access to mining software and anything related. I would say there will be something completely new as quite a lot of people think Proof-of-Stake isn't better alternative.