Yeah, Kipruto has ran 7:44 outdoors, but that was back in 2012. As an 8:01 steepler, 2-time World's silver medalist and with the crazy kick he has over the last 200, he should be able to go much faster.
Also might want to keep an eye on the Ethiopian Dawit Wolde. He pretty much soloed a 3:54.02 mile at an indoor meet in Ireland (that you can watch on espn3 or the espn app) a few days ago, and has ran 3:33 outdoors.
He said in an interview after that he was leaning towards trying to make the Ethiopian team over the 5000 instead of the 1500 for Rio, so he must feel good about his strength versus speed.
I had never heard of the guy, but wouldn't understand that decision at all. There are pretty much only 2 top 1500 guys in Ethiopia (Wote and Gebremedhin) but a whole slew of 5K guys.
If you look the guy up, he actually has a pretty crazy resume, from 3:33 (2012), 13:17 (2014), 60:46 (2012) and 2:10:04 (2015). Over 3K he has ran 7:48 indoors and 7:42 outdoors.
He looked great in that mile a few days ago though, he might mix it up and get nice time, assuming the race doesn't end up a jog-and-kick.
All that said, I expect Farah to win easily ... fast race or slow race. Most the interest to me will be the guys racing behind him.