Ceballos + Ndombele is pretty big to be honest.
Think it will only be one of them unless Eriksen leaves. Ceballos would make even more sense as he could help give their game more structure at times and they don't have a type like him yet.
Ceballos plus saving the Ndombele money and investing that in another attacker to more often bin that muppets Alli would be better business imo as things stand.