Sadly, according to some new intel it turns out the LG D820/821 is not the Nexus 5 after-all. Just last week we shared the FCC filing for a new LG device with high-end specs which had the LG D820/821 model number. Most of the industry speculation suggested it was the new Nexus 5.
Unfortunately, @evleaks was able to confirm that this new model was not the Nexus 5, but is simply a CDMA version of the LG G2. Of course, this new info doesn't mean the next Nexus won't be an LG device, as it still could be. It simply means the Nexus 5 (if it is an LG device) will not be one of these. We can probably readily assume that whichever OEM builds the Nexus 5, it will come equipped with Android 4.4 KitKat. As always we will share any details when they become available.
Source: @evleaks