Well when you've been going at it for 25 years and 11 albums (in March 2005), you've got a lot of ground to cover. If you were to break it down in eras:
U2 will play something from 80-86
New Years Day, SBS, Pride, with a possibility of Bad
I think Pride is really their most mainstream track from this era, it was their first top 40 hit in the US, it's been a staple for them live for years, I think they will play it over the others.
U2 will also play something from that 87-93 era
One, Streets, With or Without You
I think they go with Streets, it's universally accepted by most fans as their benchmark live song, it's the song that will never leave the setlist.
Those two, IMO are definite.
After that, you'd figure they might play a ballad One/WOWY
And they might play another uptempo rock song NYD/SBS/BD
I can't see them being able to summarize their career in 3 songs, on second thought, I don't know how they would not play One.
So that's my ballot: Pride/One/Streets in order, induction by Stipe.
That's what I think they will do, if it were up to me it would be Until the End of the World/Bad/Streets induction by Brian Eno.