I knew NE DOT plan to upgrade US-75 from Nebraska City to the Murray as a 4-lane divided expressway. https://dot.nebraska.gov/media/5786/us-75-from-nebraska-city-to-murrary.pdf I won't be surprised to see a alternate corridor combining US-75 and US-73 between Omaha and Kansas City might act as "Alternate I-29" when I-29 is flooded.
The upgrading of US 75 from Nebraska City to Murray is proceeding in three phases:
https://www.acppubs.com/articles/hawkins-construction-company-partners-with-nebraska-dot-to-convert-us-75-into-four-lane-expressway
People were already using US75 South of Nebraska City when that flood happened as I-29 was pretty much closed north of St. Joseph/Mound City vicinity. I remembered reading articles back then saying that the traffic was pretty bad through the towns along that stretch.
IMO, NDOT and KDOT should plan (at minimum) to add passing lanes along the road between NE-2 and US36, when funding allows, for whenever the next flood event happens. A 4 lane expressway would be preferred but that's probably too expensive to do at once.
Btw, that year I took U36 west from St. Joseph out to Seneca and then K-8/NE-50 as that was closer to where I was heading in Omaha. It wasn't too bad except for when I got stuck behind some slow vehicles north of Syracuse.