I think Kuma will die at Egghead Island. Too many death flags going off right now IMO. Whether that be directly by Saturn's hand or by Kuma finally succumbing to however many wounds he's endured over the last 24 hours on his rapid trek across the globe getting there, who knows.
I do think though that before he dies, Kuma will likely use his DF powers to eject Luffy's wounds and exhaustion and enable him to jump back into the fray in Gear 5 to properly fight back against Saturn. I also wouldn't be surprised if Kuma gets some sort of big hero moment when he first arrives on scene by saving Bonney from the firing squad that Saturn currently has trained on her.