Zoro would be deeply affected. He has sworn to follow Luffy and his death would be a huge blow. He might feel like he failed in his duty to protect the captain. He would likely become more withdrawn at first, but then focus on getting stronger to avenge Luffy if there was someone to blame for his death.
Well, let's consider each character. Shu would probably be indifferent at first, but as things progress, he might start to worry about how it could disrupt his lazy lifestyle. Ayato would be envious and might try to cause some trouble for Subaru. Laito would make inappropriate comments and try to get a rise out of them. Reiji would be the one trying to keep everything in order and make sure they follow proper procedures. Kanato would be a bit of a wild card, perhaps being overly possessive or acting out. Yui would be relying on Subaru for support, and Subaru would be ready to fight anyone who threatened his family.
Nami would be inconsolable at first. Luffy has always been there to protect her, and his sudden death would leave a huge void in her life. She would probably cry for days. As time passed, she would remember all the things Luffy taught her about courage and believing in oneself. Nami would start to take on some of Luffy's leadership qualities in a way. She would be more outspoken about her plans for the crew and more determined to see their dreams through. She would also keep Luffy's memory alive by telling stories of his adventures and his selfless acts to new people they meet on their journey.
Nami might be shocked at first. She'd probably look at Luffy with wide eyes, not believing what she just heard. After all, Luffy is not the most romantic or traditional suitor.
I took a trip in my Subaru Crosstrek to the coast. The drive was beautiful. The car handled the winding coastal roads with ease. I could feel the power of the engine when I needed to overtake other vehicles. And the view from the car was just stunning. I stopped at several lookout points and just enjoyed the moment, all thanks to my Subaru.
They might be shocked. Luffy's Gear 5 is such a powerful and strange form. In the fanfiction, characters could be amazed at his new abilities, like his cartoon - like movements and seemingly limitless power.
Nami would probably be devastated. She has been with Luffy through so much, and his death would be a huge blow. She might become more withdrawn and serious, as Luffy was often the one to bring out her lighter side.
Nami would probably be shocked at first. She might worry about how this would affect Luffy's journey to become Pirate King. But then she would likely start thinking about practical things like how to take care of the baby on the ship. Sanji would be over the moon, seeing it as an opportunity to cook for a new little life. He might also be a bit jealous that it's Luffy and not him having a baby with Hancock.
Blackbeard's crew is also a diverse bunch. His more aggressive members like Burgess might be eager to start a fight with Luffy's crew. However, some of the more cunning members could be thinking of ways to use the situation to their advantage. They might try to manipulate Luffy or his crew into making mistakes. And if Blackbeard decides on a certain course of action, his crew would generally follow, but there could be some internal dissent depending on the situation.