IMHO, we'll not see the fucboy again because many JP comments now said they didn't want to see both Sakura and fucboy again. They're now most hated characters. You can read many hated comments for seeing the sex scene of Sakura and fucboy on chapter 131. They even said "disgusting".
Sakura apperance in chapter 132 also got many hated comments. Readers don't want to see both Sakura and fucboy in Grapara anymore. I think Kodansha (publisher) is not as stupid as the author.
So, what we will see is an attempt to make people dislike Sakura less because the publisher needs to sell volumes 13 and 14. Volume sales is the primary source of revenue for the publisher.
If I'm not wrong, the online readership generates very little income and 70% of revenue goes to the author. While the author receives only 10% from volume sales.
Hence, the publisher is extremely concerned about volume sales figures. When currently pre-orders of volume 13 were low as an effect of the chapter 129 , they secretly pressured Airi Katsura (sensei) to salvage the situation.
The sex scene between Shinobu and Fumi is only a superficial fix. Killing off Sakura in chapter 129 and 130 was the major blunder that caused Grapara to collapse and lose popularity. So they now need to restore Sakura's image soonest.
So, the fucboy character who raped Sakura and caused her to be hated in chapter 129 will not reappear to further enrage readers. And since the author has stated she won't revise chapter 129, she is forced to alter the current storyline instead.
We'll see Sakura again in order to lessen the anger against her which will impact volume sales no matter she will end up with Shinobu or not.