Inter is looking really good this season. Juventus is probably the second best still. They will have to improve their performance to actually get on the first position of the table. And by the looks of it, it is going to be hard because Inter is not going to make it easy for them at all. But I expect Juventus to start performing better because they do not have any pressure from other competitions as you said. So it should not be a big problem for them in my opinion to actually improve their performance further.
The season is still long and there are still many matches that will be played by these two teams so I am also quite confident that Juventus will continue to perform quite well this season in Serie A. Because apart from Juventus not having pressure in other competitions, Juventus will also not ignoring every opportunity they could take advantage of this season to continue chasing Inter Milan at the top of the current standings. Even though Inter Milan itself is still performing quite well so far, if one of the key players is injured, I doubt Inter Milan will continue to improve as it is now.