Eh. I'm not saying that Chinese leadership doesn't enjoy the ability to poke the US, and play that up for domestic political reasons, but indications I've seen are that they've been getting sick of North Korea's shit. Check their language in these periodic crises from the late 90s until now -- they practically sound like they're on the US's side now compared to the late 90s.

There's a more practical reason for them to hope the regime doesn't fall: it creates a refugee crisis on their border and the CCP governance model is 'stability uber alles'.