Lets check the pros and cons on flywheel energy storage and whether those apply to domestic use (source):

Compared with other ways to store electricity, FES systems have long lifetimes (lasting decades with little or no maintenance;[2] full-cycle lifetimes quoted for flywheels range from in excess of 10^5, up to 10^7, cycles of use),[5] high specific energy (100–130 W·h/kg, or 360–500 kJ/kg),[5][6] and large maximum power output. The energy efficiency (ratio of energy out per energy in) of flywheels, also known as round-trip efficiency, can be as high as 90%. Typical capacities range from 3 kWh to 133 kWh.[2] Rapid charging of a system occurs in less than 15 minutes.[7] The high specific energies often cited with flywheels can be a little misleading as commercial systems built have much lower specific energy, for example 11 W·h/kg, or 40 kJ/kg.[8]

• long lifetime -> that would be a nice thing but not of the utmost priority. With 100,000 cycles (minimum taken from Wikipedia) it significantly outperforms rechargable battiers such as Tesla's Powerwall 1 with 5,000 cycles within warranty. Other sources report a design life time of 30 years (though for utility scale storage systems not for residential use)
• capacity starting from 3 kWh -> A few to a few tens of kWh would put it well in a useful range for domestic use.
• Specific energy of 11 Wh/kg (typical commercial system, value taken from Wikipedia) -> With an usable capacity of 13,5 kWh at 120 kg system weight Powerwall 2 outperforms commercial flywheels tenfold.
• price -> While I did not find any good numbers for small home-use flywheels but I somewhat doubt they beat the 5.5k US-$ for a Powerwall 2.
• round-trip efficiency (charge/discharge) of up to 90% -> in the range of what Powerwall claims (92.5%, source)
• large maximum power output -> Again, no numbers for smale-scale systems but a high power throughput is not a primary concern for domestic use (7 kW peak; 5 kW continuous of the Powerwall seem quite reasonable for that use case).
• safety -> It's hard to compare the risk from batteries (fire) to catastrophic failures of flywheels (kill'em all projectiles from a disc turning at 50,000 rpm).

In conclusion: with all the effort put into development of rechargeable batteries and upscaling of a whole industry to massproduce and market them I would doubt that flywheels are ever going to fly (pun intended) any time soon in a residential setting. I would rather expect to see them as grid energy storage in utility-scale levels that would benefit from the advantage of a high power output and where a higher capacity warrants the complexity of such systems (moving parts, vacuum, mag-lev).

Lets check the pros and cons on flywheel energy storage and whether those apply to domestic use (source):

Compared with other ways to store electricity, FES systems have long lifetimes (lasting decades with little or no maintenance;[2] full-cycle lifetimes quoted for flywheels range from in excess of 10⁵, up to 10⁷, cycles of use),[5] high specific energy (100–130 W·h/kg, or 360–500 kJ/kg),[5][6] and large maximum power output. The energy efficiency (ratio of energy out per energy in) of flywheels, also known as round-trip efficiency, can be as high as 90%. Typical capacities range from 3 kWh to 133 kWh.[2] Rapid charging of a system occurs in less than 15 minutes.[7] The high specific energies often cited with flywheels can be a little misleading as commercial systems built have much lower specific energy, for example 11 W·h/kg, or 40 kJ/kg.[8]

• long lifetime -> that would be a nice thing but not of the utmost priority. With 100,000 cycles (minimum taken from Wikipedia) it significantly outperforms rechargable battiers such as Tesla's Powerwall 1 with 5,000 cycles within warranty. Other sources report a design life time of 30 years (though for utility scale storage systems not for residential use)
• capacity starting from 3 kWh -> A few to a few tens of kWh would put it well in a useful range for domestic use.
• Specific energy of 11 Wh/kg (typical commercial system, value taken from Wikipedia) -> With an usable capacity of 13,5 kWh at 120 kg system weight Powerwall 2 outperforms commercial flywheels tenfold.
• price -> While I did not find any good numbers for small home-use flywheels but I somewhat doubt they beat the 5.5k US-$ for a Powerwall 2.
• round-trip efficiency (charge/discharge) of up to 90% -> in the range of what Powerwall claims (92.5%, source)
• large maximum power output -> Again, no numbers for smale-scale systems but a high power throughput is not a primary concern for domestic use (7 kW peak; 5 kW continuous of the Powerwall seem quite reasonable for that use case).
• safety -> It's hard to compare the risk from batteries (fire) to catastrophic failures of flywheels (kill'em all projectiles from a disc turning at 50,000 rpm).

In conclusion: with all the effort put into development of rechargeable batteries and upscaling of a whole industry to massproduce and market them I would doubt that flywheels are ever going to fly (pun intended) any time soon in a residential setting. I would rather expect to see them as grid energy storage in utility-scale levels that would benefit from the advantage of a high power output and where a higher capacity warrants the complexity of such systems (moving parts, vacuum, mag-lev).