My pessimistic self feels like the short-term effect is that it sets a deadline by which oil companies know they have to extract and sell all the existing oil on the planet, and a doubling down on increased emissions now because fusion will solve it eventually.
There are hundreds of years worth of oil deposits (possibly more) even at current usage rates. "Selling all the oil" isn't in the realm of possibility.
As much as necessary, sure. Oil it turns out is pretty useful in many different industries and contributes to higher standards of living for the vast majority of the world. It isn't some inherently evil technology or resource. Still, it's going to take decades to transition to electric regardless of any breakthroughs in the meantime.
