You're confusing pumped storage with river dams. The geography for pumped storage is abundant, river dams not so much.
>Battery storage is entirely speculative so far.
In 2012 maybe. These days grid level battery plants are deployed routinely.
>Whilst nuclear is a proven baseload source
At 5x the cost per kwh, according to lazard.
Baseload also means "requires peakers". That means gas or...batteries.
When french nuclear plants go down for maintenance the country chews through ungodly amounts of gas. Some of their plants have capacity factors of like ~80% - not much better than high performing wind farms.