I don't know about Sasuke/Sakura being planned. There's NO WAY Kishi looked at that and said "yeah, I got something here."I feel like Sasuke/Sakura was always planned.
Zutara was kind of "Wat?"
Reylo was absolutely out of nowhere and I hated how it dominated Star Wars tweet feeds to the point I quit Star Wars over it. I can't even understand the mindset behind this because it also makes my brain itch in bad ways.