Current LFP batteries should last multiple decades as a home battery. The already have low flammability. The price is getting more affordable. They could just be part standard of a home electric system in a decade or two, like a whole-home surge protector.
Low rates of spontaneous thermal runaway, sure, but they still are extremely flammable if externally ignited or physically damaged. A house fire that could otherwise be put out might turn into a full disaster. An earthquake that physically damages the battery pack could cause a fire that would have otherwise not happened. A flood or minor tsunami might allow for early evacuations and most lives saved, but now the entire town is on fire instead of just water damaged, if every house has a massive lithium pack in their basement.
It also depends a lot on use case; for example, for home electricity storage (like a PowerWall) I would gladly give up energy density for safety. If there's some battery tech that can handle 50000 charge cycles and completely non-flammable but weighs 100 tons and has 10% of the energy density of Lithium, I'd gladly make that trade. Maybe build part of the building out of it.