The 24 year old Turkey international, who arrived on Merseyside late in August, has taken a while to settle in but has scored three goals in his last two starts.
"I don't look beyond the loan period because there are lots of things which will determine whether he ever came here (permanently)," said the manager.
"One has to be availability. Jose (Mourinho) may decide after one year playing he is really the type of player he wants around his squad.
"Two: He might not be affordable. Affordability is important as well.
"We'd all love Lionel Messi but whether you can afford him or he's available is another thing."
He added: "All I can concentrate on is Sahin coming in here and helping him become the best player he can possibly be.
"If he finds he enjoys it here and he fits into the way we work, which I am sure he would do because he is a good guy and understands the game tactically and is prepared to fight for the club, then that is something come the end of the season we will talk about.
"But at this stage it is way too early. He is just starting to get up to speed fitness-wise but what he is is a real good guy and you have seen his performances."