It is sad to see Sadio Mané go, but Liverpool got a decent fee for him and he departs under amicable circumstances, which is increasingly less common these days. There is no such thing as finding a 1:1 replacement for Mane, Salah, and Firmino - but between Diogo Jota, Luis Diaz, and Darwin Nunez, Liverpool have three very talented strikers who could represent a new generation of a top-class attack at the club. Time will tell.
Now we just need to find a replacement for Divok Origi - arguably a tougher task. 😄
Good strikers who can get you 20+ goals a season are a rare commodity. Especially in a tough league like the PL.
In MLS, 10 goals a season is 'good', especially if the player does other important work like holdup play, PKs, dead ball delivery etc. Only the top 13 strikers in the league scored more than 12 goals last season. So in essence less than half of the teams have a striker scoring much over 10 goals.
In fact I would argue there isn't a pro league in the world where you can expect any striker to hit 20 a season, with a couple obvious players being exceptions.
Porter has used a variety of formations after going with a 4-3-3 for a couple seasons. Now we see more often a 4-2-3-1 or some sort of 5-man-midfield-based system. But in all cases we've always had a traditional number 9 leading the line unless we were forced to adapt due to injuries/international duty. So even if Cucho doesn't score a ton of goals, a player of his type is essential to the overall system and creates space for other attacking players like Zelarayan, Santos, Etienne.