... だろうが、... だろうが => Whether it's ... or ... N3
Demonstrate by example
たろう => probably is ~ N3
Speculation
…だろうに => surely… N2
Speculation
かろう => May be... N2
Speculation
~であろうとなかろうと => whoever; whatever; however; even ~ N1
Innocent
だろうか  => I wonder... N4
Speculation
ことだろう => Perhaps... N3
Speculation
だろう => Probably A N4
Sentence Endings
ことだろう => how…!; what…! N2
Exclamatory
…たら…だろう => If only... N3
Condition (condition contrary to reality)
…ば…だろう => If ... then perhaps ... N3
Speculation
だろう => Is that right? (Reconfirm) N5
Confirm