I would love to see crews, contests and more events like spot battle added to the game. Personally I'm not a fan of the loot boxes but they could add a 'crew' currency as a third currency and have a new crew box or crew store where you can choose which crew outfits you want to buy. These crew outfits/boxes could be updated every month. The more events you play and win the better outfits you unlock. It would be cool to see different real crews with different colours skating around. The current challenges are already becoming extremely repetitive.
I remember skate 3 even had teams. Previous skate games definitely had better online game modes. As of now we are missing spot battle, 1 up, deathrace, hall of meat, street contest, vert contest, s.k.a.t.e and more.