If the extra point is a 40-yard FG, then teams would probably just go for 2 every time. Statistically they'd speaking they'd probably score more points.
Statistically speaking they wouldn't. Team convert 2 point conversions roughly 45% of the time. 42 yard FGs are successful in the 85% range. A 42 yard PAT would, on average, produce 0.85 points. A 2 point conversion attempt would produce, on average, 0.9 points.
It's nearly a wash. We'd probably see a lot more 2 point conversion attempts, but not every time. There would still be situations where a single point would be advantageous (say you just scored to go up 27-20 and have a choice between an 8 point lead and a 9 point lead).
It would challenge coaches in a new way.