If Metternich had not stood in the way of (in their view) progress, Austria might have reformed, dealt with the problems of nationality better, and the First World War may never have happened.
Not quite. With Metternich gone, Kolowrat is likely to assume power within the Empire. A less ambitious or controlling man than Metternich, but nevertheless one of the arch-conservatives of the era.
I
would argue that it would mean better things for Austria, but mainly because the rivalry between those two pretty much locked down the Empire. Emperor Ferdinand's reign (with the secret regency and all) certainly didn't help.
Hell, either Kolowrat or Metternich being unchallenged rulers of Austria would lead to some reform, limited though it may be. Though I'll admit familiarity only with Metternich's plans and not Kolowrat's, being only able to surmise from his actual actions that I know of.