Non-energy uses of fossil fuels are not problematic from the point of greenhouse emissions.

If we stop burning fossil fuels and get energy from renewable sources, the remaining hydrocarbons will probably be used for plastics, chemicals and so on. If they aren't burnt this is fine.

It also probably makes more sense to use fossil fuels for applications where density is critical such as aviation, offset with carbon capture, rather than to leave oil in the ground and synthesize jet fuel using renewable energy.