As with so many big questions, the answer is "it depends". But as things are, the great majority of the human race is due for disaster of one kind or another, sooner or later. The first and probably worst disaster will be repeated famine, the second will be wars over water and possibly oil. Famine will occur because increasingly hot dry climates will support less and less agriculture. Sea level will rise, leaving smaller areas for people to live in, and to grow food crops. Edible fish will become extinct.
The very small remainder of the human race which survives these disasters will number a few million, and will have to adjust to poorer food and a very much lower birthrate, and a very small area of land to live on.