PRC has a habit of pushing its forces down other people's throats. If say Uzbekistan had a border with PRC, and PRC cited ISIS takeover and sent a couple of divisions into Uzbekistan, who would be able to deter PRC? No one.
Yeah, he has two daughters. Stuff gonna happen in Uzbekistan soon. This is a new headache for Russia. The good news is, Uzbekistan does not share a border with PRC.
I will opt for the option of nepotism. Karimov's immediate successor should take over. I don't want ISIS or its affiliates taking over. If that happens, I hope a joint Russo-Kazakh-Kyrgyz force occupies it.