The question is not _can_ the US build a newer bomber. The question starts with identifying threats and then the best ways to deal with them (both effectiveness AND cost).

Bombers are for a traditional war against fixed targets (think WW II). Those are quickly becoming a thing of the past because not even Russia can really go toe-to-toe with the might of the US military as it currently stands. What is needed are more quick-reaction, cost-effective tools. Drones piloted (or aided) by spotters on the front lines seem to me to be a far better proposition all around except in the extreme cases like delivering so-called "bunker-busters" or tactical nukes. But the price tags for these packages are absurd for the use (IMO).

I'm all for maintaining a robust self-defense capability, but I have to question mega-projects like this strictly from an economic perspective.