if history repeats 2018 will not rally, it will simply be a consolidation year. weak hands will be shook out. difficulty may even fall on many alt coins. maybe even bitcoin. we may have seen the low at 6k and we may even test 5. going to 4 would be an absolute floor unless we are destined to go to zero. i'm sure a lot of miners would shut down. network traffic would fall. 80-90% of altcoins would die.
I agree, in fact I think it's a win for Bitcoin if this year maintains the consolidation and holds it's price at $6,000 - $8,000. This can prove to the world financial press that 2017 wasn't a farce or a fad, that Bitcoin is here to stay. It also proves to the next wave of investors that Bitcoin is worthy of their attention.