If we're able to make hydrocarbon-synthesis from CO2 efficient.... we're still going to need to source the hydrogen somewhere.

But if we do that using electrolysis (with renewables), and are able to create more energy efficient CO2 capturing processes, I could see synthetic hydrocarbons as a viable fuel option in the future. The thing is: They're stupidly good at being stable, energy dense, energy carriers. We also have a lot of infrastructure in place to handle hydrocarbons already.

In principle, synthetic hydrocarbons could be part of a zero-emission cycle, where we capture CO2 and electrolyse hydrogen with renewable energy, and use the hydrocarbons as an energy carrier. But if we go that way, we're definitely going to have to research efficient hydrogen production, and probably storage as well.