The world needs a new source of energy, an unspillable source.

biofuel or electric cars, which is most likely to take over?

What is more likely to happen, a new fuel is found are/or different ways of producing it and piston engined cars are powered by this better fuel similar to the way it is now or electric cars? Obviously both are going to happen but which is going to completely take over the auto industry in the future? This is excluding possibility of hybrids.
If electric cars take over whats going to happen to mechanics? And everything I’ve been learning for years will be like a waste if electric cars become the norm so I’m really worried about this.