I don't really get the logic of the highlighted passage, mate. I think we DO have some serious attacking talent in this team: players like Coutinho who can make a goal out of nothing, Firmino with his great all-around quality, Sturridge, now Mane and possibly Wijnaldum (and who knows, maybe Coric too). None of them have a work-rate anywhere near Henderson's or cover nearly as much ground – only Lallana comes close and he is the least prolific attacker of that group. In midfield, I feel that Can is at his best when allowed to pick his spots to make decisive interventions, as he does – he is not somebody who can (or should be asked to) run non-stop for 90 minutes. Part of it is just physique – there is a reason guys who run marathons look leaner than those who push weights. Can's body is closer to that of a weightlifter, that's why he can push people out of the way, but don't expect him to cover every blade of grass while carrying that frame.
So actually we have a deficit of players like Henderson – Milner and Allen can do it to an extent, but Hendo has more tools in his arsenal (speed and long-range passing to name two). Given how crucial this kind of player is to Klopp's system, this is probably why he sought to bring in Dahoud as a priority, not to replace Henderson outright (from what I've seen of both players Dahoud possibly has a higher ceiling, but he is NOT better than Hendo at the moment), but to compete with and supplement him. Hendo really shouldn't be lumped in with Lucas and Allen – he has more to his game and unlike them, he has one genuinely world-class quality – the ability to run with maximum intensity for all 90 minutes.
Like Ryan, I have absolutely no doubt that Klopp would LOVE a player like Henderson when he's in good form (like he was in 2013-14 and 2014-15 – that's more than "one good season"). It's just bad luck that he was struggling with chronic injury just as Klopp came in, but even then I loved his attitude – you could tell he knew he wasn't anywhere near his best and sometimes he seemed visibly in pain, but instead of feeling sorry for himself he just tried his best to help the team. He is a great kind of character to have in the team and I think fans owe a bit more loyalty to a player who gives nothing but 100% (even when he is feeling 50%) every week. We demand loyalty from them, so let's not discard a player at the first sign of trouble.