Gravity is a curvature of space-time in the theory of General Relativity. It is not known what it will be in the final theory. It could end up being a "force" a

Gravity is a curvature of space-time in the theory of General Relativity. It is not known what it will be in the final theory. It could end up being a "force" after all, or it could be that all forces are "curvatures" of a sufficiently complicated understanding of "space time", in which case force would be likely be redefined to be "curvatures" of space time anyhow, or other possibilities. It may be easier to understand this point by looking at the current theory of Quantum Mechanics, in which gravity doesn't exist at all. We are not entitled to make conclusions about gravity from that fact, since the conclusion would be "gravity doesn't exist", which is clearly false.