Only if its a free battery. Otherwise, its an income stream with an up front cost.
An old tesla battery with only 50% capacity remaining is still perfectly good for this kind of use even if not so great for driving.
Maybe briefly, especially where retail customers with some installed renewable generating capacity can leverage the latter to take advantage of net metering laws designed to bring renewable capacity to the grid, because otherwise their stuck buying at retail and, if allowed to sell back at all, selling at wholesale.
Bur cheaper batteries mean proper utility players (e.g., a joint operation of PG&E and Tesla) are building large, purpose-built storage facilities, often colocated with generation facilities, with lower marginal costs for real estate and interconnection than separate facilities and better access to financing than small operators.
Storage is going to be a big industry going forward, but the period where home storage (or storage by anyone but major utility players) is a viable financial hack rather than just a backup plan for grid failure will probably be brief unless artificially subsidized to encourage distributed storage.
Those 90% cells will also have a pretty nice degradation curve as most of the loss happens within the first few years of operating.
A home battery in many places is basically free money. Renewables mean there is an extreme oversupply at some times and an undersupply at others. Owning a battery hooked up to the grid means you buy power at oversupply times where the power goes in to negative pricing and then sell it back at other times in the same day where it is very expensive.
Reusing old car batteries for this purpose might become the next bitcoin mining with warehouses full of repurposed batteries buying and selling power.