Marcelo Brozovic has been an unremovable pillar of this Inter team this season. He directs, runs and manages these games brilliantly and there is no replacement on the current squad (no disrespect to Borja Valero).
For the upcoming season, the Croatian deserves a partner who is capable of doing those things to take a load off his shoulders. In a 4-2-3-1 formation, assuming that Spalletti is still at the helm for next season, Manchester City midfielder Ilkay Gundogan would be perfect.
The German’s wage is less than ideal though because he has an expiring contract in 2020 and is demanding City €9M a year to renew: clearly too much for the financial status of Inter. This is by far the biggest stumbling block because finding an agreement with City should not be a problem for someone that has the right attributes, characteristics, experience to raise the bar at Inter.