Grujic could become a perfect long-term replacement for Henderson, given the age profiles of our DM's:Grujic scored a matchwinning header for Hertha Berlin yesterday against Frankfurt He's been a starter for them in their last 3 match unbeating run. I'm sure Klopp is monitering the situation closely. Some hope for him perhaps.
On the other hand Allan is having a mare loan spell for Frankfurt, out with a knee injury and only featured in 4 games this season.
Worth noting that a similar player in Nemanja Matic only broke through at Chelsea at age 26.
Given that he has both Fabinho and Henderson ahead of him it would make sense to loan Grujic out for next season as well (he even spoke of staying at Hertha another season if they qualify for the Europa League), after which he'd return to the club ready to seriously fight for a place at age 24, with Henderson entering his 30's (obviously presuming that he continues his development whilst on loan).