I too think it'll sell out. When we last went to Anfield - granted it was a saturday - in 91 we took about 5,000. We were only getting roughly 8k at home in those days remember.
It will sell out. After high points fans have taken theirs, there are many many 1,000's of others who can't afford s/t's or regret not getting one, who are desparate to go & will take the balance.