[Pecos]

Wouldn’t a cargo plane with bomb bay doors cut in the fuselage have the same structural problem as a converted airliner? Somehow, you have to make up for all of the longitudinal members that have been removed. Although, skipping to the end of your post - the idea of a new subsonic tactical bomber might make sense for some roles.

[yefragetuwrabrumuy]

Some of the advantages of the B-52 is relatively low and inexpensive maintenance compared to the modern bombers, some of which must even be stored in temperature and humidity controlled hangars.

It also consumed a heck of a lot of fuel, sometimes needing refueling as soon as it reached altitude.

So a modern design would likely have modular everything, so after a given length of time the entire aircraft would be replaced a piece at a time on a wear and tear depreciation schedule. Estimated price about $75m a plane.

Next would be significantly improved fuel efficiency, which is just normal engine evolution, nothing special.

[Neidermeyer]

Somehow, you have to make up for all of the longitudinal members that have been removed.
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Maybe you could load and drop bombs vertically instead of loading them horizontally,, have a whole lot of openings that don’t intrude on the structural members.. or have a mechanism that squirts them out a opening under the tail.

[Oztrich Boy]

Wouldn’t a cargo plane with bomb bay doors cut in the fuselage have the same structural problem as a converted airliner

Don't cut. add on under