Only specs I've really seen leaked are 5.7" screen and based on the unannounced "Mate 8" model.
From http://www.breathecast.com/articles/nexus-2015-rumors-news-leaked-video-reveals-specs-of-purported-2015-huawei-nexus-video-30407/
The Mate 7 had a 4100+mah battery, speculation is that this could have the same or bigger.
Anything passed through the FCC for a US and/or Sprint version that covers the Spark bands? I'm in the market for a new phone this fall and will be going off contract, buying a Nexus.