No-go for Samsung's Batteries in Tesla's Li-ion Battery Packs?

Interesting (and contradictory) things are happening right now on relation Tesla Motors - Samsung-LG-Panasonic.
It seems that Panasonic batteries are, and will be Tesla's exclusive li-ion battery cell supplier.

You can read very good article about latest development here:
Elon Musk confirms that Samsung’s battery cells will not be used in Tesla vehicles, Panasonic gets exclusivity