I’m so glad you put this up because i have always wondered if Indiana was anything more than a driveby fantasy just to sell more spots.That may be all it is.
I think it's important, but it isn't determinative. If Cruz wins Indiana, it costs Trump some momentum, but probably not so much that Trump can't get to 1237. And at the same time, if Trump wins, he can still (theoretically) be blocked from getting to 1237.
OTOH, if one follows the general flow of the primary races, this one is over. Trump has 90+% chance of getting to 1237, even if he loses in Indiana.
I wonder, sometimes, who or what has most influence in setting the establishment line. When it is clear that Trump has the nomination "on paper," which group has the most power in setting the story between then and the convention? There are many different possible story lines, between "unite behind Trump" and "unite to block Trump".