I guess this was coming. Opera was on a long and painful road to irrelevance, right from when they threw away all their amazing work to become yet another chrome variant minus the most useful features that really made Opera what it was - respected, lightweight, fast, and supremely customisable.
As for this acquisition, it's a surefire way of alienating whatever userbase they managed to hold on to. Qihoo is a purveyor of questionable software to put it mildly, their servers are in mainland China and are probably controlled by the CCP/PLA unit 61398, and I sure as hell won't trust them with anything.