Let's say you're a scientist. You do research. Then, due to medical advances you become effectively immortal. Are you going to stop doing research? Why would you if that's the work you love? After several decades you might decide to give another career a go, maybe become an artist, but this tendency would probably be countered by immortal artists who decide to give scientific research a go.

But I think that in the future our ability to perform scientific research will be massively increased through the use of Artificial Intelligence. The process has already begun with AI used in many fields, and I think this will be the main determinant of the rate of research, not cultural changes resulting from extended lifespans.