You'll definitely have chemical degradation within those 10 years, but even assuming $71/month over 20 years + $0.017/kwh, that's still pretty expensive for an urban environment, though may work out for suburban and rural (I pay about 11-12c/kwh in my 2br apt in Jakarta), I still think there is still plenty of future opportunity for electric utilities (esp for industrial applications that will require peaks alot higher than residential).

I really don't see costs coming down that much in the next 10 years for electrochemical batteries.