well we were gonna sign Emre Can most likely, now that that seems to be off, we could simply be looking at a different cheap DM, which Mascherano is. if Emre Can was to be our only midfield reinforcement, then id rather have Mascherano for 2 years anyway, and then bring in Mandragora after that. id be happy if we keep everyone this summer, bring in Caldara, Spinazzola, maybe De Vrij, sign Mascherano and spend on a great RB finally.
another thing, look how Heynckes rejuvenated Martinez by moving him back to DM (@bayernfan can confirm), Mascherano paired with Pjanic in a team like ours will bring the best out of him again