motnot, nlp has not given any indication that NW will not re-book this person on an earlier NW flight. That does not seem to offer a viable alternative for this person. But I do not understand the 5 hour layover at DTW. The 4:10 p.m. flight from RIC arrives DTW at 6:01 p.m. The legal connection would be NW's 7:25 p.m. flight to LAS arriving at 9:03 p.m. A 5 hour layover is not even considered a legal layover on a domestic routing. As to re-booking on CO, no, that is certainly not required of any airline to do when there is advance notification of a schedule change or flight cancellation.
What you describe is not at all uncommon, and rarely is the customer satisfied with the options offered. In a situation like this, the airline's only obligation is to offer alternatives on their own airline or offer a complete refund. In most cases, a refund isn't a viable option because the alternatives are more costly.
So my suggestion is to call back and ask to be re-routed on NW 1417 connecting to NW 1195. Now if they tell you that your fare class isn't available on 1195, that's when I'd raise a ruckus. They are absolutely obligated to re-route you that way if any coach seat is available.
[This message has been edited by Sheryl (edited 12-03-2000).]