I think both Rice and Partey can compliment each other very well in that midfield.
The focus for Arteta will be to make Havertz and Declan Rice develop and Understanding with Martin Ødegaard. Partey was almost out of the team, but it looks like a last minute decision has kept him in the club, for the now until maybe there is news of an interested club. Rice, Havertz and Martin Ødegaard will have another chance when they play against Barcelona later this week. They were an embarrassment in their last game against Manchester United, maybe the loss will force them to find that connection and get more involvement in the game to show Arteta that what he has in his mind for the team next season will work.
There is no way Harvetz,Rice and Odegard will be able to defeat Xavi's midfield.Arteta is trying to build a kind if connection between them,but I think the person that would have been in that midfield is Partey instead of Harvetz who hasn't understood the pattern of Arsenal play.Harvetz is not strong phisically,and so he cannot control the midfield when
person like Partey stands there.Uptill now,I am still not convinced about Hervetz delivering for Arsenal day in day out
It is true that Arteta has a good plan for Arsenal next season,but according to what we have seen in the preseason so far,they are not like the way the were last season.There preseason was one that they really enjoyed,because they won all their matches and loose none.It will be good if Arteta goes to the transfer market and sign atleast one more midfielder like Douglas Luiz should Incase injury comes on in.