This is good, but someone has pointed out that Amtrak has an aversion for adding and dropping cars, in general. And splitting trains. Don't know if that is actually true or not, but given the Albany shuffle for the Lake Shore Limited, it's pretty evident that perhaps they just don't know how to do this maneuver expeditiously. New Haven used to change out an engine in 7 minutes, and we were on our way.
Case in point: The through cars between the Capitol Limited and Pennsylvanian. The PRIIA had suggested it back in 2010, it would add no equipment, fuel, or track rental. Yet Amtrak still hasn't done it.
How would it not require additional equipment? You'd have to send at least a coach (several more cars) from the current
Pennsylvanian on west to Chicago, but more importantly, unless it were a coach-only through train you would also need three (minimum) Viewliner sleepers which Amtrak simply doesn't have (but will shortly).
As for Chicago to Florida service, a split at Cincinnati would only serve to further increase the utility of the
Cardinal; There is no call for your continuing to attack such a hypothetical service.