There are other games EA produces than NFS.
One of the most current games is EA's purchase of the iOS game "Real Racing 3".
Yes, this game does provide nowhere near the immersion simulators on big screens, using FFB wheels, racing seats and alike but honestly, I very much enjoy a quick spin with Real Racing on an iPad.
The game includes a few Porsche models, all of which are modelled very nicely for what the limited hardware can provide - some even sound rather good as well (but many unfortunately do not have the distinct 6-cyl boxer sound, they should have) and most do have a rather likeable feel (in what the platform and limitations can provide).
The game runs on a "free to use" model and promotes buying in game credits (for rather steep prices) to achieve quicker what one can actually achieve using the game entirely for free.
Looking at the reach the iOS platform has to potential end customers, especially with a game that is provided for free, I can absolutely understand any decision, steering towards prolonging exclusive licensing to Porsche brand vehicles to exclusively one player in the market.
I do love Porsche - their cars are my favourite cars of them all. I am one of the people who would actually sacrifice ALL other available cars in GT if I could have all Porsche cars in exchange (sounds boring for most but not to Porsche nuts I believe).
It is a real pity that in 2014 we do not have detailed modelled Ruf Porsches and other elaborate re-engineered Porsches in an effort to satisfy some Porsche love with GT6.
I would pay for DLC Porsche vehicles and would be willing to pay a high price, if these cars are modelled (and SOUND) to the highest standards.
Unfortunately this is very unlikely to happen. It is only a game of economics of how many potential Porsche buyers are reached by a licences product.
An expensive DLC on a video game console is highly unlikely an interesting marketing medium for a manufacturer.