There are simply other proven money-making priorities at the moment.
This is one of those things where all the right pieces need to be in place first. If not, then it doesn't make good business sense to proceed. There's been talk for some time regarding Porsche's intention to build a direct mid-engined supercar competitor to the Ferrari 458 Italia. Last we heard, Porsche would supposedly make a final decision regarding the project in mid-2014. Well, that time has come and gone and there's still not been any official announcement. Only silence.
But now a report coming from Autocar claims that said Porsche supercar remains on the wish list. Dubbed the 988, the project apparently has been sidelined in order to focus time and attention to the next generation Panamera, due in 2016. Also of greater importance is a redesigned Cayenne, refreshed Boxster/Cayman and 911, as well as new engines and transmissions. All of that costs money and Porsche needs to focus on its existing lineup. If the 988 were to come to fruition, it was rumored power would come from a 4.0-liter V8 that'd produce around 600 horsepower and 400 lb-ft of torque. So is the project dead entirely? Probably not, but it's not a priority at the moment.