Don't like this idea. Its not their irrefutable greatest song, and isn't the one song everyone's dying to hear. This isn't Skynyrd's Free Bird. U2 has arguably dozens of amazing songs, Streets is just one of them. I want to hear WOWOY more than any other song at any given U2 concert.
I've been to a few concerts (not U2) where the band opened with half of a signature song and then ended with the other half, and to me it diminished that song rather than highlight it.