Besides a GOP primary opponent... no one.
The average voter in Indiana has no idea that Curtis Hill is a Weak Incumbent™.
This race has IN-9 written all over it: vulnerable to a Democratic challenge under conventional wisdom, which is increasingly shown to be worth very little as Indiana settles comfortably in the Republican column down ballot.
You're from Indiana, explain why.
Partly, this comes down to what Joshua said: most people aren't following this scandal closely enough for it to change their vote. I'd be surprised if a majority of Hoosiers could independently name the Attorney General or, vice versa, tell you exactly who Curtis Hill is or describe the allegations against him with any degree of specificity. That being the case, it's hard to see where the fuel for a "Republicans for [insert Dem nominee here]" campaign is going to come from. Glenda Ritz managed to pull off a win in the 2012 Superintendent race—in an environment much more favorable to Democrats than 2020 is likely to be—thanks to the support of teachers' unions and parents upset over the Common Core. Who are the anti-Hill Republicans who are going to bring the same degree of passion and commitment to this race next year? Unlike the SoPI, the State Attorney General doesn't have a direct impact on most people's lives. We've already seen that politicians and voters are willing to ignore sexual harassment charges as it suits their narrative. Especially considering the charges were originally made two years before the election, I doubt this will be a burning issue in most voters' minds—except maybe for those who were never going to vote for Hill anyways.
Finally, the state Democratic party is an organizational wreck and is unlikely to have the funds to mount a serious challenge to Hill, especially with a popular incumbent like Holcomb leading the opposing slate.
This. It would take a Democratic landslide nationwide to take down Hill, especially considering Holcomb will likely wipe the floor with his opponent.
Holcomb literally only won by 6 in a Republican tilting national environment, no more than the amount that Donnelly lost by in a Democratic leaning national environment. He is not Safe.
He "only won by 6" when it looked the week of the election like Gregg had a good shot at winning. The Trump landslide kind of condemned Gregg, but he was the best candidate of the 3 major Democrats running statewide in 2016 between him, Hillary, and Bayh.
As far as this race, I think this is the only noise the Democrats will attempt to make statewide in 2020. Brian Howey has reported that Democrats are considering putting up a sacrificial lamb for governor and choose to focus on Attorney General. It's to the point now that some think Buttigieg is going to use a failed presidential run to run for governor, which I don't see. I think Buttigieg is trying to get out of Indiana as fast as he can politically.
Holcomb had asked Hill to resign after the House investigation into it. This was refused. It's part of an intra-party squabble that's not been resolved yet. Hill was considering running against Holcomb in 2020 in a primary pre-scandal, and I think the scandal as well as horrid internal polling numbers Hill backers ran showed that's not going to happen. Hill gets more interest than he would otherwise because he's an elected black Republican, but if you didn't follow politics intensely, which most people don't, the voters in 2016 didn't know he was black, they think he's just a guy named Curtis. Harry Truman is stating as much.
Last tea leaves I saw on it was people in the state GOP were asking Todd Rokita to consider running for Attorney General. I think Hill being on the ballot in 2020 is opposed by Holcomb, State Chairman Kyle Hupfer, and State House Speaker Brian Bosma. They need a candidate to put forward at the Convention however.
