I think what's stymied U2 lately is that they don't know what sound to make. Do they want to do a Rick Rubin album, or do they want to do a musical soundtrack. Do they want to do a dance album, or do they want to do an ambient, meditative album.
U2? Listen: At the end of the day, you are primarily a rock band. You should do a rock album. With lots of guitars with different sounds throughout (i.e. a reintroduction to The Edge). And when you reach back to revisit the past this time, let it land somewhere in the 90's. Add some dancier stuff, a few songs with new-wave synths and a few songs with electronic beats. Have a bunch of chanting (i.e. "Volcano, etc,) in half the songs. Heck, why not go ahead and throw in a couple of your ballads. But then, with a nod to your political and outspoken roots, include a scathing, biting, loud song about someone who is unnamed in the lyric but is obviously Donald Trump (i.e. "Bullet the Blue Sky," etc.). And after it's all said and done, say you've had precedent, and did it all again, just like you've done before.
And put it out soon. You're running out of time.