This is actually perfect. All of the majors today (including Dubai) with pacemakers are going out in 61:30 atleast in desperate WR attempts that always ends in blow ups (though this might end due to Kipchoge, but not enough time has passed). Farah hung on after a 61 flat in worse conditions to run a 2:06, so an even split 2:04 is definitely possible. Rupp will have his chance to prove himself in a "true" major marathon. Also don't forget Kirui, who should definitely be favored over Rupp.
Also, don't forget Dubai breakout star Geremew who also held on for a 2:06 after an ill-fated record attempt a berlin 2017, and held on at a suicidal race in Dubai for a 2:04:00. If they truly go out in 62:00, he is probably the favorite to win IMO (though Dubai winners tend to fall off).
Don't forget Chicago is a fast course (Course Record is 2:03:45 set by the former WR holder Kimetto with an even split)
My prediction
1. Geremew 2:03:30 CR
2. Farah 2:04:24 EU
3. Kirui 2:04:57
4. Rupp 2:05:50 (No American record sorry)