Would I make good profit, for example, by the end of 2018 if I buy domain names now and resell them at some point when the price goes up ?
Could potentially be a profitable idea. The problem is it's already 2018 and crypto started in 2009. I'm fairly certain that you aren't the first person to think of this after 9 years. All the good crypto domain names will by now have probably already been taken.
I guess if you can find some that are expiring then you could get lucky.. But the fact that they are expiring means that nobody wants them.. lol.