If is difficult to reach 20000$ mark because there are various news which make the Bitcoin market down and the reasons behind the fall of Bitcoin is country don't accepting the regulation,frauding happens,blockchain issues,and the news from various country who are banning crypto currency in their country.
But surely when bull run start we will see a Bitcoin will reach 20000$ mark in next few months. By seeing today's market we can able to think it will cross 2000$ in a bull run.