What this episode was all about was Sai's POV on Team 7. Sai's character development has drastically improved over the course of time, and this episode chronicles his character development. Sai's POV on Team 7 was absolutely excellent. His POV on Naruto and Sakura's relationship was awesome and interesting to see. Sai feeling guilty because he thinks he made their relationship worse was well played out. Anybody in Sai's position and seeing it from his POV would feel the same way too. In which point, we can emphatize with his position as an observer of the Team 7 dynamics. That's what Sai's role in the story is,
an observer. And the one thing I loved about this episode is the build-up for the peak of his development in the War. This episode was such an obvious build-up to his development that it's almost not funny at all. The artbook scene was an excellent reminder for the anime-viewers about that particular plot point for Sai's character which will soon come up in the War. Lastly, by topping it off with that wonderful Neo-Team 7 picture was very moving.
As for that picture, I will give my two cents on it. Why not Sakura that's holding Naruto's hand?? Simple. From Sai's POV, Sasuke is the one Naruto has the closest bond with. Sai drawing himself holding hands with Naruto is to symbolize that he wants to forge a bond with the center of Team 7, Naruto. As the center of Team 7, by forging a bond with him, you forge a bond with Team 7 as well. This is what Sai's wish is. To forge a bond with Team 7 and Naruto.
And if we see it from Sai's POV, Sakura would come last. You may argue that Sakura is on equal footing with Sasuke for Naruto. But then it wouldn't make sense if Sai drew Naruto with an extra hand, wouldn't it
?? If he drew Sasuke and Sakura on both sides of Naruto, that would just make Sai look like the outsider. Remember, like I said before, what Sai wants is to forge a bond with Naruto and Team 7. Another reason why Sakura would look like she comes "last" is because, for now, the closest bond he (Naruto) has is with Sasuke. And Sakura holding Sasuke's hand makes sense. Because, from Sai's POV, Sai sees that Sakura still has
some feelings for him. Whether it's romantic or not, we don't know.
Remember that we are seeing this from Sai's POV. And think about it this way, if that image of Team 7 shattering in Naruto's mind is an indication that Sakura is not the fangirl we used to know, this can be used to surprise Sai that what he did was actually positive for their development.
EDIT: As for the preview, yes!! that badass Genin grandpa returns!!! I loved that guy!! I'm guessing he was really popular that guaranteed him a recurring spot.