Red Bull have been having a tough time with their Renault power units this year, they have suffered more packaging issues and failures than any other team. This has left them short on engine components and almost guarantees that they will be taking grid penalties for using extra components later in the year.
However If you believe that Renault have no chance then you clearly have a short memory. Red Bull have won the last four drivers and constructors championships with great reliability and often in absolutely dominating form. They have bent over backwards to accommodate Newey's increasingly tough packaging and cooling demands and of course to create the best engine maps to take full advantage of the blown diffuser era.
Of course as we have moved into this new engine formula, Renault have struggled despite being the key instigator of these new regulations however once the engine freeze is relaxed at the end of the year a key opportunity opens for Renault to close the gap on Mercedes and I really wouldn't bet against it. Next year the engines will be much closer and allow the field to close up.
The rumours at the Red Bull Ring this weekend are that Red Bull are keen to ditch Renault in favour of building their own engines, indeed lots of engine part manufacturers have been spotted in and out of the paddock having meetings with Red Bull personnel. Although building your own engine is no easy feat, otherwise you'd imagine McLaren doing their own too (as was also rumoured before the Honda comeback announcement) and if you think Renault are behind Mercedes, imaging how much further back a Red Bull engine programme would start, it would take a good few years of pain to get up and running, and thats a lot worse than the one bad year with Renault!
I think in the grand scheme of things, Red Bull are making lots of noise so that they can reduce their engine bills and get them badged as Red Bull Infiniti engines as Infiniti are part of the Renault-Nissan Group.This would make sense and spread Renault's involvement in F1 around their brands a little more. It would give them more marketing bang for their buck. I can only see the Red Bull and Renault parting ways if Renault decided to leave the sport completely.. and that would really be a shame, not only for Red Bull.. but for F1 as a whole.