checkdb killed/rollback - stuck for 3 days

I have a scenarios whereby a checkdb on an 800GB database was cancelled and 3 days later, there is sessions stuck in "killed/rollback" state.

I ran 

select blocking_session_id, wait_time,wait_type, last_wait_type, open_transaction_count, percent_complete,estimated_completion_time, cpu_time,total_elapsed_time, reads, writes, granted_query_memory, parallel_worker_count
FROM SYS.DM_EXEC_REQUESTS
where session_id in (66)

and i see the wait type is EXECSYNC,  percent complete 10,05694 and doesnt change, estimated completion time is rising, cpu_time is not changing, reads and writes are not changing either.   

I dont want to restart the Instance as i am afraid the database will go into recovery and it will take the same time to recover and users will not be able to access, for now, at least users can access but it is extremely slow. 

Will it eventually complete? or its hung ?

Any advice ? 

ilikefondue