I can't be entirely sure but i don't think nukes get destroyed by other nukes, therefore you can still counterattack, if i m wrong then yeah that shouldnt happen.
You know, you might be right there. Units like bombs, missiles and airplanes tend to be ignored by this kind of stuff. Haven't really tried it, I tend to rush for the UN and get nukes banned before anyone can build them. (Which by the way doesn't make sense neither! If anyone wants to break the treaty, let them! Right now the only way to break non proliferation is to call for the same vote again and then veto... but if I was going to veto against the world's will anyways, why not just build those nukes anyways and have the same result immediately?)
Still, it doesn't feel the same... having your totally destroyed cities launch a volley of nukes. I actually especially liked the "self-destruct" option which doesn't seem to get any attention in this thread. A last chance, possibly before you make the choise, you'd get a prediction of the nukes effect. Like "Sir, Washington, New York, Boston, Miami and Las Vegas will lose 85% of its citizens and buildings, its surrounding areas will be unexploitable for the next 200 years. We will lose 90% of our military units in those cities." "LA, Houston and Detroit will be wiped off the face of the earth, all civilians, buildings, military and culture will be lost, its surroundings uninhabitable for the next 3 centuries!"
I don't know about you guys, but if I see that this -the destruction of the last 40 hours of gameplay- is the result of me feeling like tossing a couple of nukes; and I know I can stop it beforehand and try for a conventional war instead; I'd abort the nukes.
Also, I agree that post-fusion wars would be hard to declare and that currently there isn't much incentive NOT to start throwing nukes, but given enough feeling of consequences (diplomatic, economic and military) to nuclear war and leaving enough space for a conventional war without so heavy drawbacks, wars would/should still be possible.