Here's some epic reporting on Ukranian corruption under Yanukovych. Here's an even more epic long form report on the same subject. The main point is that widespread corruption under post independence governments metastasized under Yanukovych into something far more centralised and systematic. The Ukranian state changed from being a means of facilitating corruption to become a system of theft in itself, and in so doing eventually created an unstoppable opposing coalition. This reminds me a bit of the Italian theory of virtuous minorities: to a certain extent the corrupt need the honest to keep the machinery ticking over and preventing the corruption moving from transactions in which paying parties actually get what they pay for to the kind of situation where people have to pay simply to function. Inter-alia, this is what Xi is trying to prevent in China.
My guess is that things will revert back to steal-more-quietly mode, assuming Putin's engineering of a brother's war doesn't have revolutionary consequences. One advantage here is that a pro-Western orientation changes the framing. Our enemies are kleptocrats. Our friends are embarking on a difficult reform process. They need our encouragement.