No, he will go for a Eubank Jr rematch. By the time that is all wrapped up GGG will be slated to face Canelo. Saunders has stated recently that he is a year away from fighting Golovkin.
The better question is will GGG fight BJS? GGG has avoided slick defensive fighters like the plague...
Some plastic belt doesn't add much. A fight between 2 top 5 fighters is what makes it good. The people in the crowd don't care if Saunders still has the belt or just vacated of his own volition.
I think Sanders would fight him, he wouldn't bottle it like Canelo but Saunders isn't an idiot, he knows what a huge ask it is at this moment in time and he will want to make some defences first, get some money in the bank and secure his future and I wouldn't blame him.