What has been said of this deal of why or why not it's happening from the Russian side has contradicted itself. From the beginning the reason said of why it's not happening is intellectual property issues. Then we hear the Russians are confident it cannot be copied. Then what held up the deal in the first place? If China cannot copy then there's no problem selling it. China supposedly wanted the engines to copy. It's believed China has a problem with engine development and if Russian thinks it cannot be copied, again... what held up the deal in the first place? From the Chinese side has there ever really been an official statement China is seeking to buy the Su-35? All information about this deal seems to have come from everyone but China. It's been said China wants the engines but Russian won't sell without the Su-35. Isn't that the heart of it? Russia is trying to sell the Su-35 and needs an initial big buyer. They say the Su-35 beats all challengers but a few in this world. China buying it would certainly spur buyers especially if it were like how they sold the better tech Flanker MKI to India and not to China. I'm sure the export version of the Su-35 that would be sold to China isn't going to be the best one.
Now what has the Chinese side said? Nothing but some denials to certain reports I believe. If China cannot copy the Su-35, what's holding up a deal? The most obvious answer is they don't want it. Maybe it's true China just wants the engines but the Russians have linked it to the sale of Su-35s. Geo-politically why would China want the Su-35 so Russia can get others to buy? The most likely customers are going to be potential adversaries of China that are scared of China possessing the nearly unbeatable Su-35 to where Russia will most obviously offer a better version than in possession of China. The only customers that would buy the Su-35 would the ones afraid of China. The propaganda that goes along with this whole story is China is not satisfied with it's own domestic fighters hence why they want Su-35s. That would be the Plan B sales pitch if China rejected the Su-35 from the beginning. Get the most likely target customers to buy something Beijing wanted because China's own fighters weren't better.
If a deal comes for the Su-35, it'll probably come by as a side deal for something else that China wants. If Russian tensions with the West has opened Russian technology to China, it'll probably be a part of that. If the Su-35 deal were that important to China and Russia has always been willing, it would've happened long ago since it can't be copied.