Asterix as I expected, having Merino on the pitch saw more positional interplay between him and Rice compared to playing Partey. I think that is a sign of things to come once we have a fully fit team.
More to the point you made, if we continue to get results with this setup (and as others have mentioned, the fluidity and chaos we get from Havertz and Trossard really confused PSG), I can't see Arteta changing it (ie. we'll rotate Partey and Merino until the latter settles).