When you talk about day trains across Ohio and Indy etc., keep in mind that Amtrak altered the Pennsylvanian's time - when it ran to Chicago for a few years - pretty regularly. Ohio and Indy DID have daylight running times, at least on the schedule. But nothing materialized with traffic. Grant it, most of the schedules were geared for M&E traffic, but I do think Amtrak tried with variations in the schedules.
The Pennsylvanian - when extended to Chicago - would leave the endpoints at 6:30 a.m. (arriving in Philly at nearly midnight in one direction and 1 a.m. in Chicago in the other direction). And that was if the train was on-time. When I rode the train, most were Philly to Pittsburgh riders or intermediate point riders. The end-point riders chose the overnight service with a train that offered more amenities - the Capitol Limited, Three Rivers, or Lake Shore Limited.
If you are looking for a "day-time" ridership through Ohio and Indy, I think you need a day train that connects from Chicago to the Empire Corridor at Buffalo. New York State NARP would like to see one of the Empire Corridor trains extended at least to Cleveland. But I am not sure if I see this in the near-term.
And in addition to providing a day-time train from perhaps Cleveland to Chicago or Buffalo to Chicago, Amtrak should really bring back the Three Rivers and have the Capitol Limited leave earlier, followed by the Lake Shore and Three Rivers.
The problem I forsee is that all these trains - Three Rivers, Lake Shore, Capitol Limited, and day time train across Ohio and Indy is that it would all be concentrated on the former NYC water level route. I doubt the freight trains are going to allow this many passenger trains on their tracks without some sort of additional track building coming about.
On the other hand, the Capitol Limited and Lake Shore are riding the markers of each other by a couple of hours. I don't see this as a positive move. Something creative has to come out of train running between Chicago and the East Coast. Whether it's combining trains and then splitting them, adjusting schedules, or something completely different, I am not sure. However, I don't think Amtrak can afford to lose the "overnight" market between Chicago and the East Coast where the model basically is board in the evening, sleep while the train travels, and awake at your destination the following morning. May work westbound, not eastbound.
I also would not dismiss Amtrak's efforts of establishing a daylight train via the Pennsylvanian across Ohio and Indy at one time. This did not produce too much traffic.