I just got off #6 in Mount Pleasant 4 hours late. It departed Grand Junction on time but lost 2 hours, plus the 1 hour tacked on to the schedule, between there and Denver. Track work overnight in Nebraska and between Ottumwa and Mount Pleasant accounted for most of the rest.
The conductor announced that those connecting to the Cardinal would transfer at Galesburg to a thruway bus and meet #50 in Indianapolis. #6 arrived in GBB at 4:27 pm in plenty of time to catch the bus scheduled to depart at 5:10 with a 11:25PM arrival in Indianapolis in plenty of time for the 11:59 train departure. So, no problem, unless you don't look forward to a 5+ hour bus ride.
I believe the bus is a common carrier, not an Amtrak captive. So I don't know what would happen if #6 doesn't make the 5:10 departure.