According to TheDetroitBureau, Cadillac is analyzing the prospects of a bigger plug-in hybrid and also a production variant of the breathtaking Elmiraj concept.
The company's global sales chief, Bob Ferguson, told TDB that although it's too early to provide details about a new plug-in hybrid, he did say that he "could certainly see a larger vehicle, something even more luxurious" than the recently introduced 2014 ELR. The car would probably use GM's Voltec plug-in hybrid platform found inside the Volt and ELR, but most likely it would be a next-gen version with more power to match the increased size and weight.
When referring to the Elmiraj, Ferguson said it "wasn't made just to be a concept car, it was made to be operationalized" and that he would "like to see it in showrooms as soon as possible." In other words, the Elmiraj is a production-intent concept based on an existing platform and if green-lighted for production it would be slotted above the XTS.