All depends how long that switch-over takes and what technology comes out on top as the most efficient/cost effective and reliable. In case you haven't seen this before, the following is in regards to the hybrid dual combo EV/NG-fuel cell technology, Toyota has just very recently decided to pursue. Got to hand it to the Japanese. They have set some of the most followed trends in the auto biz since the oil embargo days of the 1970s. It's literally going to be a race to see what tech comes out on top first!

http://www.thedrive.com/tech/9738/toyota-experimenting-with-natural-gas-fuel-cells