I'm not convinced. The examples I can think of with the AAA team in the same Metro area (Atlanta/Gwinnett, Texas/Frisco) are considerably larger Metro areas with larger populations within an hour or two's drive.
As to minor league affliliates driving major league fandom, I suspect it makes less difference than we think. There's a really cool Web site that shows fan affiliation by ZIP code, at least as measured by Facebook: https://www.nytimes....,40.074,-96.760. In Omaha, for example, the Royals don't show up in the top three favorites, despite being the KC AAA team for more than 50 years and being the closest team geographically. One has to go south of Lincoln a bit before the Royals start to register.
As to those mentioned, the Lincoln and Sioux Falls Metro areas rank between 152 and 182, and neither have populous outlying areas. FWIW, Cedar Rapids is between them, so if you're going to consider either of the former, you might as well consider the latter, and I don't think that's realistic.
By population, if you want a larger Midwestern city that's under-represented in the MILB scene, Grand Rapids is a better choice. It's the 51st-largest market and currently only has a Class A team. It also has significant outlying population and frankly, a fair amount of wealth/opportunity for corporate sponsorship.