It’ll be interesting to see what role hydrogen plays. Prices for using it to store energy are currently a couple times battery energy storage systems, and the component parts are not getting cheaper very fast (turbines + storage + electrolyzers), whereas battery storage is rapidly falling in price. But as you point out: we know how to use hydrogen/synthetic methane/ammonia as a storage asset if we need it.

I think it will be difficult to satisfy global storage demands with lithium batteries. But most countries already have infrastructure to store a couple of weeks to a couple of months worth of methane. Perhaps it makes economic sense to just use that infrastructure and pay the 60% conversion loss. Maybe other battery chemistries will be better options.

I’ve seen analysis that says we have enough lithium globally, especially if we use existing working recycling techniques widely. And there are other battery chemistries with earth abundant materials (e.g. iron redox) that could ease the lithium supply concern. But I think you’re right that geopolitics will play a huge role. As we’ve seen with the war in Ukraine and Russian gas, resources are not uniformly distributed, and we can’t rely on frictionless international trade to work consistently.

There is some leeway in global warming as on net the earth sequesters more carbon the higher the atmospheric CO2 levels, it’s just nowhere near fast enough to keep up with current output.

Unfortunately we already emitted enough carbon to force pretty catastrophic warming, so we'll need to become net negative for at least a couple of decades before we can talk about low net positive emissions.

You are far more optimistic than I if you assume net negative is a possibility any time soon. A significant reduction in methane might be possible which would provide similar benefits.