No one technology is accelerating fast enough. But I think battery storage has amazing potential for scalability. It is very suitable for mass production in a factory and produces small components that are relatively fungible. Battery storage sites can be built anywhere, require little civils works, have tiny environmental impact and are very quick to install. And they have the benefit of research and production for cell phones and cars. Massive scalability is hard to predict in advance but is definitely possible. Look at how many billions of arm chips are shipped every year.

We definitely do need pumped storage. Although big civil engineering projects tend to be slow and expensive in most developed economies. And how much of the world actually had the right terrain? My guess is that we will see a few massive projects at one end of a HVDC link rather than scaling up.