Given that the only time they were used in a war it was directed at cities, many people believe that nuclear weaponry is cumbersome, strategic, and massive in effect. This is hype; barring terrorism, the most likely use of nukes in the future are will be attacking data/ energy infrastructure on the surface and in space. One does not need multiple megatons to render whole satellite constellations useless from a relatively long distance. Nukes, while sexy on film as city leveling fire pillars, are at their most useful as a disparity leveler in terms of force count.

This is all conjecture, of course. I think/hope nukes really come into their own as mining and propulsion resources.