Newcastle United’s hardest task in the transfer window is resolving their striker situation. Alexander Isak will lead the line for Newcastle United next season, as he prepares to kick on even further after the best campaign of his career. The 24-year-old scored 25 goals in all competitions last season, which resulted in Dan Burn calling him ‘world class’. Now Isak is back with Newcastle for pre-season, where he is working alongside Callum Wilson. The 32-year-old is Newcastle’s other forward, but it is unclear how much longer that will be the case. Callum Wilson’s Newcastle future is up in the …