Most airlines probably have a protocol on what to do if this happens. Death during a flight, while rare, is always a possibility. My guess is they took the deceased up nearer to the front of the plane where seats are roomier. Perhaps a blanket was put up, in consideration for passengers who are apt to freak out over a natural but unfortunate event.
A good pilot would probably say something on the loudspeaker to sum things up and help the staff/ passengers return to more routine thoughts as much as was possible. Wine was made available.
One would hope. But, I was on Olympic Airlines landing in NY when an old man keeled over on the floor, dead or doing an excellent imitation of dead. No one said anything. We had to step over him to exit the plane.
The staff has medical equipment including an AED on the aircraft. They will ask if there are any medical personnel on-board to assist in the emergency. If a nurse, paramedic or doctor step forward, the air crew are thrilled to hand the emergency over to them.