In the long term, complete displacement of hydrocarbons from the economy is probably the end goal. However, we are nowhere near being able to do that right now. Obviously for the billions of vehicles on the road and the current grid power generation we need not just solar/wind generation, but also massive amounts of grid storage (or massive increases in nuclear) and vehicle batteries. But in industry there are tons of chemical processes that also require hydrocarbons that we haven’t found suitable replacements for yet.
Because it’s not clear how fast we can get absolutely massive amounts of grid storage or nuclear deployed, finding ways to make effectively carbon-neutral natural gas/petroleum is a good step in the right direction, where we can continue to use some hydrocarbons without a net increase in greenhouse gasses in the atmosphere and oceans.
It’s also not clear if we will be able to replace all of our current petroleum reliant industrial processes with non-carbonized alternatives, and in those cases, this will be the absolute best case for us.
No, I think we are quite near to being able to achieve that.
There may be billions of vehicles on the road, but as soon as the system fails to be able to upkeep all the deployed capital required to maintain them in operating condition (road resurfacing, parts manufacture, refinement and transportation of fuel, maintaining the value of currency in order to motivate the workers to participate in all of the necessary steps, security from hostilities, roads not being flooded/melted, and so on). In such eventualities sizeable portions of the fleet may be rendered inoperable quite quickly and cars will be displaced, out of necessity, by walking.
What you're making is a different point, it's not that we can't displace hydrocarbons, it's that we can't displace them with something equivalent-or-better. We can probably displace cars with walking, concrete structures with ad-hoc shelters, and hospitals with prayer. That is all not just very achievable, but has actually been increasing in inevitability during our prior decades of "inaction" (obviously you can't really call it inaction when we're taking positives steps to hasten these outcomes)
Because it’s not clear how fast we can get absolutely massive amounts of grid storage or nuclear deployed, finding ways to make effectively carbon-neutral natural gas/petroleum is a good step in the right direction, where we can continue to use some hydrocarbons without a net increase in greenhouse gasses in the atmosphere and oceans.
It’s also not clear if we will be able to replace all of our current petroleum reliant industrial processes with non-carbonized alternatives, and in those cases, this will be the absolute best case for us.