Yeah I agree, as part of a balanced energy strategy it could work in some areas. I've seen some more chatter around molten salt batteries recently too.
The ideas are old, it's just turned out to be a hard nut to crack economically. It's one of those renewable holy grails that have seen a lot of investor money disappear. Reminds of Carnegie, CCE, here in WA. Buyer beware in those areas in particular!
Turning the gas up or down to precisely meet demand remains too convenient and cost effective.