I think Derya's transfer to Vakifbank makes a lot of sense. Gabi can do everything and no locals will be as good as her anyway, so Idil Naz was not making any sense at all in that squad. Same for Busa, she is only needed to sub for Frantti in the backrow. They needed someone who could support attacking and having a local to do that is priceless for them, so they can use Chiaka now in the local league.
I also agree that Gabi will probably slow down quicker than we think in upcoming years. The only player I can relate to her is Gözde. They both rely so much on their jumping. Of course they are very technical too, but combining the technique+that jump was what makes them one of the best spikers. With her technique and smartness, I am sure we will see Gabi in top teams for 4-5 years more, but we will be asking why she attacks not as good as before, and that's simply due to her jumping abilities slowly downgrading.