Today the Diamond line rebooked me on a new domestic itinerary due to a 3.5 h delay of one of the flights, and my V-class ticket remained V class. My #1 upgrade position on the original flight evaporated, and I was something like #10 for 3 seats available on the new flight... So yes, no "bumping up" due to IROPS anymore, it seems, and if your new flight is elite-heavy, then as a Diamond you are SOL with respect to upgrades.