As I've said before, it's not a surprise and I'd imagine it was a two way decision. Mane's form picked up when he was moved centrally because it was less physically demanding than playing on the right but who knows how long that would have continued moving forwards. Playing in attack for us is a young man's job and there was no chance that we were going to give out big contracts for all our forwards. Salah is the priority, and I wouldn't be shocked if even his new deal doesn't happen, meaning Mane was never getting that final big pay day with us. He was faced with a choice of a shorter contract with us or a new challenge and the way we are run, I can't imagine a new challenge fazed us.
Whether it's Mane and Salah or Kane at Spurs, these players are at an age where they're going to need replacing sometime in the next few years and it's far easier to replace them by receiving a fee for them than getting that extra year and them leaving on a free or a much reduced fee.
I've always questioned the logic of us signing an out and out centre forward in the past but I wonder if that is that is how we replace Mane. Even if he signs a new deal Salah won't be the same influence on the side in 1-2 years and with Firmino already playing a lesser role, maybe we end up with a slight tweak to hoq the front line plays.