Any other athlete is fair game too. Rudisha would have the best shot in my opinion, but maybe there is someone else who would be faster in the sprints and still have enough endurance for the marathon. Here are the qualifying times, best as I could find. Note that most of them are from 2008, because for some reason I couldn't find them for 2012. But this is a rough exercise, so it doesn't really matter.
Event 'A' 'B'
100m 10.07 10.28
200m 20.30 20.75
400m 45.00 45.95
800m 1:46.50 1:48.50
1,500m 3:39.00 3:43.00 30
5,000m 13:33.00 13:50.00
10,000m 28:15.00 29:00.00
Marathon 2:19:00
One note: for the marathon, he needs the marathon standard. The 10000m or half-marathon options don't count, even though those would get you in in the real world.
My take: I don't think he'd quite be able to get it. The 100m and 200m are probably a bit quick for him, and there is not as much you can do to train these events. I predict he would get the 'B' standards, and maybe would run fast enough to qualify, but 10.07 is a pretty legit time.
I think if he were trying to do it, this would be the best strategy: he gets the 800m, the 1500m, and maybe the 400m out of the way quickly. Then he increases mileage and starts doing aerobic runs. Maybe he does the 5k and 10k if he is feeling good, otherwise he goes straight up to the marathon. He then runs a couple marathons, stops when he gets the standard, and then gets the 5000m and 10000m times if he hasn't already. If all goes well, which I think it would, he could do all this in no more than 15 months.
Then he immediately drops mileage to essentially zero, starts lifting heavy weights, and starts taking every (legal) supplement he can get his hands on. Of course he has to do this without getting injured, but my point is that he no longer has to worry about running anything longer than 400m ever again -- 200m if he has already gotten the 400m time. He then spends the rest of the time training for the 100m and 200m, and hopes that he has the speed in him.
Of course, there are lots of reasons why this attempt is never ever going to happen, and I won't get into these. I am asking you to suspend your disbelief. Do you think he would get the standards? Would he be close? Which events would be the hardest/most unrealistic to get? Would anyone else have a better shot? Remember, he is training full-time for four full years with his only goal being to achieve these standards. Cheating is not allowed, but other than that, he is doing anything and everything is his power to achieve these standards.