That plane will be flying on Mars, mark my words.
It is just such a utilitarian platform that you can't beat it for being a bomb truck. It has a long range, very good loiter times, is high altitude… Part of the B-52s survivability comes from just how high it can carry its payload. Many SAMs can't reach it. Some of the larger systems can, but those can be hammered with TLAMs or taken out using strike aircraft.
Sure, you can turn and burn on the deck with a B-1, but it's not got the altitude or loiter time of a B-52. You can park a BUFF in a figure-8 over the battlespace and give soldiers on the ground a JDAM-on-demand. Call in a fire mission using a laser designator rather than trying to hump a Javelin or AT-4 system around.
The B-2 is a fancy airplane, but is kind of prissy and likes its manicure and pedicure time. There are only a few air bases in the world that they can operate out of (well… I suppose you can do just about anything with an unlimited budget and a need to redeploy a whole maintenance wing to a very advanced tent). They are, also, an extremely heavy bomber. Whiteman had difficulty with the airstrip because where they would set down put ruts in the pavement. Had to completely re-engineer the concrete to handle them.