Not expecting much of anything to happen in the final April 30th debate based on the one I attended this past Monday. But my guess at this point is Braun wins this due to being considered the most electable. The reason Donnelly is in this seat to begin with is Republicans nominated someone that turned out to be unelectable. And since it's a competitive 3-way race, he only needs 40% to win most likely. The thing that gives Howey pause is there's hardly been any polling by independent orgs and it's believed there are a ton of undecideds.
Indiana doesn't make polling easy, so its hard to tell who will win. I will say that I'm pretty confident the primary electorate in Indiana is more right wing then we give it credit for. They still gave Cruz 36%, when it was obvious Trump was going to win. They also kicked out the incumbent, putting is in this position of 2018. This may be a challenge for Braun.