I think things will depend entirely on how we plan we will play next season.
We have two main formations: 4-2-3-1 and 4-3-3. Klopp obviously tried to play 4-2-3-1 at the start of the season and it was good for some time, but eventually we reverted back to 4-3-3.
I'd add that Werner is not Firmino's backup, he is Salah's backup. In terms of play style, he resembles Salah much more as a pacey forward. Firmino is a space creator, a very, very different kind of player.
As I said a few times, I doubt we will ever play regularly with Salah as RW in 4-2-3-1. We've never seen something like that under Klopp and the manager already said that Salah is more dangerous closer to the goal. When we play 4-2-3-1, Salah is the main striker, meaning that Werner would only be needed as a backup in 4-2-3-1.
In 4-3-3 (Klopp's main formation since he's become Liverpool manager), we play with Firmino as a false 9 and he is by far the most important piece of the puzzle. I'd argue that Werner is nowhere near the kind of player who could replicate Firmino. Werner is not very good creating space, his technique is average at best and he is not exactly a very bright playmaker. He is good at running and finding some space for him to play, with the help of Poulsen, who's very good in the air and at holding the ball. The one who create space at Leipzig is Poulsen, Werner is the main striker, usually coming from behind.
Nowadays, we've been using Mané as a false 9 when we need, and he's been very promising imo.
With that being said, the only place for Werner to play the way we've been using the 4-3-3 is in the left wing, and I think we have many better players we could bring in this position. There may be like 10~15 players who could do better than Werner in there.
So, imo, if we are playing mainly 4-2-3-1, maybe Werner could be an option as a backup player. But if we are playing 4-3-3 the same way we've been playing, Werner could only fit one place and there are many better prospects out there.
Oh, and imo, Werner is a striker. He can play in the left wing the same way as Origi can play there or Milner at RB/LB. It's not something natural, it won't bring the best out of him.
I'd love some striker/number 10 like Dybala, James Rodriguez, Griezmann, Jovic, and stuff like that, but the way we've been playing 4-3-3 makes me think that we are not looking for a "pure" number 10 anymore or another striker unless it's someone who can do what Firmino does. I think we will be looking for a number 8, a playmaker but also someone who's okay defensively. For now, Brandt is the one who comes to my mind, but we could also think about Zielinski, Eriksen, Aouar, Ndombele and so on.
And the last buy might be a pacey winger to replicate Mané and Salah, but also be comfortable as a rotation player only. Here there are so many options: Zaha, Chiesa, Son, Odoi, Everton, Thorgan Hazard (not pacey, though), Leon Bailey...
It will be interesting seeing how Klopp will aim to play next season. I think we will 100% bring in a another winger, but I have doubts about another number 10, 8 or a striker. We shall see.
