Townsend again shone in defeat to Arsenal.
"Can we keep him? I wouldn't have thought so," Redknapp told the Fulham Chronicle.
"He'll play in the Premier League again next year, I would think. He'll go back to Tottenham and either play for them or go somewhere else in the Prem if they want to loan him out, I imagine.
"He's been fantastic, he really has. A great loan signing. A couple of thousand pounds a week, a kid with a great attitude. He wants to be a player, works hard."