There are vendors out there who sell 2012-2013 navigation headunits that can be installed in 07+ trucks, requires a different harness and the headunit needs to be programmed with the VIN. Do a search for 2012 gm nav swap. They are pretty spendy though.
Also I will say I just moved up from an '08 w/nav to a '13 w/nav and the new style headunits are not all that special. They have a 30gig drive (wow high tech ) and XM nav traffic/weather but otherwise not much is different.
EDIT: Are you thinking of the 2015 Tahoe? That's a different beast.