Regarding NW Indiana, the appreciation here, like many parts of the US, has been on fire since 2016. When I started in 2015, a 3/1 slab house was worth about $80K. That same house now is $130K and up. The midwest has been known for being slow and steady for appreciation but these last few years have been fun. Not crypto fun but pretty good.
As far as population decline, I see it on paper but I don't see it in reality. Every house I flip goes in days to IL buyers. I have a management company and my rentals fly off the shelf too to IL transplants. South of center lake county were there's still land is tons of new construction. Hammond and E Chicago are great about knocking down old vacant houses but I can't imagine the couple dozen they do a year is moving the needle. If anything, the population decline is in Gary which based on the last census in 2010 was 80k or 16% of the total population in Lake county. So if they lose 10% which is only 8k, that reflects on the entire county. Gary has thousands of vacant houses that the city is working towards removing for new development. Their population was over 170K back in the 60s when the steel mills employed 5X what they do now. Overall, there's tons of new business development in the area. We just got a second casino, an amazon warehouse, and there's a huge project to extend the chicago train line south to reach the new developments. We're 35-45mins to downtown chicago and it's not uncommon for people to work across the border but live here where cost of living is significantly less.
I'd be happy to help anyway I can if you choose to stay somewhat closer to home.