More transmission seems like a great option, especially since the lifetime of wires is measured in decades instead of years like storage. Another point in favor of transmission is the potential to apply high temperature superconductors, which are dropping in price similar to renewables and storage and might let us increase throughput in existing rights-of-way.
Doing the analysis to figure out the value of transmission is something beyond my abilities as an armchair resource planner, since it relies on calculating network power flows over many years of forecasted demand and renewable production. Not to mention that transmission project costs are all over the place and, at least in the US, they tend to get delayed for decades. There’s some appetite to address transmission here in the Macrogrid initiative, but it’s a huge (ahem continent scale) problem.