When could we get rid of gasoline?

Now, if we wanted to, but costs might be higher.

Electric and hybrid cars need to change $5,000 batteries every 5 years. Usually a 5 year old car has devalued to the point that it is worth slightly less than $5,000, so it is not worth a new battery. So, electric and hybrid cars are dispensable.

Electric cars accelerate quickly, smoothly, and silently. Their motors are very simple and relatively cheap. Brakes can put energy back into the battery. Except for manufacturing the car (including the battery) and disposing of the car, it doesn't pollute. This means that the skies would clear up (smog only from factories, not from cars). This would result in fewer cases of lung disease

Hydrogen cars are pretty safe because the low density gas floats away. Some cars burn hydrogen and O2 (from air). Others combine hydrogen and oxygen in fuel cells, creating electricity.

To charge electric cars, they must stay for hours on a charger, or the batteries must be replaced. Light weight lithium batteries can be replaced easily. For short trips, no battery changes are necessary. For long trips, one might consider buses or planes. We need charging facilities for long trips. This means creating "gas stations" with the correct plugs to charge batteries.

What do you plan to use for food on the table. Gasoline and diesel powered farm equipment puts it there.

We could do it now, but we'd have to build a lot of nuclear fission power stations because renewables could never supply all of our power and using other fossil fuels would defeat the whole reason to stop using petroleum. We need to get fusion power working efficiently, more effort and money needs to go to researching it.

Some cars burn hydrogen and O2 (from air).
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If by "some", you mean "none", then you are correct. Hydrogen doesn't provide energy on its own and oxygen is an oxidizer. Where is the energy?

Some other fuel would need to take its place. There are alternative fuels out there but they are currently either too expensive and/or lack the infrastructure for widespread delivery.

Until that changes, we're 'stuck' with gasoline.

When all the gasoline is used up.