He doesn't need to. How many 30 goal strikers has the PL had since inception (serious Q) ? If he's getting 20-25, Sturridge 20-25, a tighter defence and more goals from midfield (which I really think we will this coming season, via Sterling, Lallana, Markovic / Shaqiri, Coutinho etc.) then we have more than covered the loss of 31 goals (it'd probably be lower this season anyway since Luis would have played in fewer PL games and it's also more than possible last season was his 'career high').
After consulting past seasons' records, I'm actually less concerned now about replacing Suarez's goals as long as we get someone who can score about 15 goals in return and we improve our defence dramatically. Here's some data for reference.
Last season, City and us got over 100 goals, which is a damn bloody rare thing in the Premier League era. Only one other team in the 22-year history of the league had scored that many goals in a season and that was Chelsea in 2009-2010. In fact, even scoring over 90 goals is rare, with City doing it in 2011-2012 (93) and Man United in 1999-2000 (97). So basically, only 4 of the 22 champions have scored over 90 goals.
Given that, is replacing all 31 of Suarez's goals really necessary anymore? Sure, if we could, we should, but based on records in the past 22 seasons, scoring from 85 to 90 goals would pretty much win the title or earn a place in the top three. So, instead of crushing Spurs 5-0 and drawing 3-3 with Palace, beating them 2-0 and 2-0 would work too.
Some sort of permutation like the following looks conservative, but I think it also looks pretty reasonable:
Sturridge, Sanchez - 35
Sterling, Lambert, Borini - 20
Gerrard, Allen, Henderson, Coutinho, Lallana - 25
Defenders, own goals - 5
So, 85 goals without being overly-optimistic (I hope) seems doable.
I've marked down Sanchez's and Sterling's numbers because past records show that the top players who played wide or alternated between playing wide and as an AM / second striker tended to score between 10 to 16 goals a season in the league. Only Ronaldo and Bale scored 18 or more when alternating between playing wide and as a second central striker. The rest? Pires had 14 goals in 3 straight seasons, Hazard (14), Mata (12), Cazorla (11), Ljungberg (10 and 12), Gerrard (11 and 16), Overmars (12), Van der Vaart (11 and 13). Giggs and Robben never even hit double figures. Silva hasn't, and Nasri has just 10 to his name as his best goals output.
Of course, past performance isn't necessarily an indicator of the future, but that then also applies to Yaya Toure and his 20 goals last season, which is such a statistical outlier for him.
