we have launched satellites with 'nuclear' batteries before and they were in strong containers. They have no risk of an explosion, this would be a good power source for whatever propulsion source comes out next.
I have no doubt that improvements will continue as usual.
Yup been around them. :) However a nuclear rocket is a completely different animal from a RTG. :) I hope you are right. However, it won't be in my lifetime. Sigh!!!!!