It seems to me that Jaguar are now the leaders in aluminium production techniques. Lotus helped Aston Martin with the Vanquish, but I believe from reports that they took much longer with resulting cost increases to design the chassis for it, and hence why the V-H platform was done in-house. I may be wrong, this is just from what I've read in the press.
Lotus, however, still seem the most capable in getting a car to handle.
As for outsourcing production for the XE, Jaguar have to be very careful as the car has to be build at least equal to it's German rivals, if not better. It really should be done in-house, and that level of quality across the board.
The design of any of it's new cars should be class leading for style, reliability and performance. Even mpg! Not an easy task, but if it does this, and I believe it can, then Jaguar has a future and will prosper. But it does need a 3 series rival.