You won't get Nissan to confirm the rumor any time soon: while it's not denying the reports, it says they're "speculation" and "not based on any announcement." NEC and Panasonic aren't commenting, either. A sale would make sense, though: the lithium-ion battery market is getting increasingly competitive at all scales, prompting even giants like Sony to sell to companies that can afford to cut costs and run on thinner profit margins.
If Nissan and NEC do jump ship, the potential buyer could have a lot of clout in the electric transportation world. Panasonic already has a close partnership with Tesla on car batteries -- it'd become a powerhouse if it could scoop up the business of another big EV pioneer. Non-Japanese companies, meanwhile, could use this to get a leg up when supplying BYD and other automakers determined to ditch gas-powered cars. If there's any truth to the rumors, you'll see the repercussions for a long time to come.