Columbus is among the city candidates to host the 2020 DNC so maybe it could help to win Ohio if the Democrats hold the 2020 DNC in Columbus.
Holding a convention in your target state hardly helps to win elections. The Democrats lost Pennsylvania in 2016, North Carolina in 2012, Georgia in 1988. And the Republicans lost Florida in 2012 and Minnesota in 2008 and New York in 2004. And so on.
To win Ohio, it's going to take a candidate that demonstrates empathy with the white working/middle class--an economic message that would appeal to the broad regions there.
The current message coming out of the national Democratic party sucks. Just look at the county returns in states like Ohio, Kentucky, Tennessee, Pennsylvania, and West Virginia from 1996 and 2016. What happened?? (This is a rhetorical question).
What it really means is that the Democrats aren't going to win the flyover areas without making a serious appeal to them--whether they are white or non-white. And that makes it almost impossible to win in 2020 (much less the Senate and House).