I have no specific knowledge which would enable a meaningful post on this thread, but on the basis that this is a technical forum my sense is that there is a great deal of speculation which is not based upon factual knowledge... so, that being said, this is plea to ask that people please try and stick to facts.
A general comment; it is curious that Schum's engine blew, but Ferrari has an incredible record of reliability (apparently 111 races without a blow!!) and therefore I guess that this was more than likely a QC problem rather than a specific design flaw; I seriously doubt that it was down to the TC system; they have been using TC for long enough that they should know the impact on the engine. I recognise that with engine homologation all manufacturers are pushing the limits, but Todt stated that this failure was a complete surprise.
Unacceptable wear rates are checked via analysis of the lubricating oil between every run of an engine and it is inconceivable that Ferrari/Shell were aware of an impending component failure and still decided to risk a failure at such a critical point of the season. Furthermore, the engines are fitted with so many sensors and failure analysis information is pretty well standard practice that the whole issue points to a more or less random failure.
now, some specific issues;
During a TC episode, they allow the valves to 'float" to vent off the compression from the compression stroke to reduce fuel consumption
According to the set of rules I read VVT technology is banned!
... causes leaner mixture, which burns with higher temp than the "normal" and creates more heat load into the system.
According to my book lean burn engines run at cooler temperatures than stochiometric mixtures. Furthermore, on the basis that it is the burning of the fuel (and the compression) which generates the heat, putting less fuel in is intuitively more likely to reduce the charge temperature than putting more in!
If I were asked to speculate (which I have not been!) I think the logical means to reduce power output selectively is to cut fuel; this is relatively simple to do, saves fuel for later in the race and makes far more sense than cutting the spark, but leaving the fuel in - furthermore, observations suggest that there is not excess fuel in the tailpipe during a TC episode as this would lead to great big flames coming out from autoignition. It would also waste fuel. On the basis that VVT is not permitted, the options are rather narrowed.
Enough... I have work to do!