It's obvious to me that you don't like EVs.  But to answer your question the battery replacement is really a non-issue.  The estimated life of my EV's batterty is 6 to 8 years (although if the battery fails in the first 6 years I get one for free).  The battery replacement and disposal cost is about $5,500.  This as really no different that when your gas vehicle's engine breaks down.  However, the real benefit for me is the gas savings.  Because I have a PV to generate the electricty to charge my EV I save on not having to pay for the electricity or in your case gas.  On the low side I figure I save about $4,000 annually in gas.  Multiply that by 6 years (again the low side of the expected life of the battery) and I have saved $24,000.  So even if I have to replace the battery after 6 years I'm ahead about $18,500.  

Here is an article on EV battery prices - https://cleantechnica.com/2017/02/13/electric-vehicle-battery-prices-falling-faster-expected/