That is not to say there won't be breakthroughs, too, that make storage even cheaper to build out. But any storage already built will continue working as well as ever. Any hoped-for breakthroughs that don't pan out will not stall build-out. The worst that can happen is costs plummeting not quite as precipitously as had been expected.
We already see utility-scale hydro storage in use, and utility-scale iron-air battery factories under construction, and utility-scale liquified-air and ammonia-synthesis plants under construction, and utility-scale investment in hydrogen synthesis and storage. Each additional storage technology that begins to come online only improves the picture.
Repeating, again and again, that things that still need to be built out have not been built out yet sheds no light.
Energy storage is far from a solved problem. You insist that it's been solved, but none of your proposed solutions have actually been implemented.