I doubt we will see Flow Batteries marketed to regular...

I doubt we will see Flow Batteries marketed to regular Residential. Flow batteries take up a lot of space, and their weight do not lend themselves to being portable for rental properties.
Premium residential and rural residential....yes.
Regular residential...no. For the majority of people, number of rental properties are increasing, and home occupier ownership is decreasing.
I also feel that the current fad of sticking a Lithium battery on the side of a regular house will fade over time as the total cost over time vs the sticker price becomes apparent. The Lithium batteries all need to be fully replaced after 10 years, with a significant recycling event/cost.
Flow batteries have a longer life and are easier to recycle.

More likely regular residential will be serviced by community batteries, that benefit from economies of scale. Think of a community battery that is a flow battery (zero fire risk), and services ~100 houses/units.
Apartment towers could have flow batteries in the basement carpark.