Per my NFL sources:
NFL, Raiders and Chargers have a deal that has the Raiders backing out of LA leaving the market solely to San Diego to move to (and with the Rams); in return the Raiders will have NFL's blessing (owners votes) to move to LV & the NFL will broadcast the Raiders games in the LA market (for AT LEAST 2 years as the defacto 2nd team so to speak).
The Chargers will then have 2 years to get a deal done with the city of San Diego. The NFL will "help bridge the gap" financially between the city & team so a vote (which would happen in 18') for a new stadium at the Mission Valley site, would be more likely to be approved by voters. If it isn't, then the team would then move to LA (and rebrand the team, leaving colors, records and the naming rights in San Diego if the NFL expand there).
IF the NFL does use money to "bridge the gap" (between $100-$200 Million dollars) for the city of San Diego & Chargers, it would be paid back over time (like the relocation fee would be, over 10-20 years).
The Rams benefit by NOT having to "share LA", which they don't want to do, with anyone and would "control their market". Rams owner Stan Kroenke would be THRILLED and would be hailed as a "savior" for having helping build 3 brand new state of the art stadiums in California and Las Vegas.
The NFL has called a special meeting next week (January 11th-13th) with the Stadium and Financing Committees to start to push the Raiders to Las Vegas to other owners as well as publicly as well. The market studies came back looking very, VERY favorable to Las Vegas and the NFL is extremely excited about the growth potential the market has (in the studies).
As I reported on the ESPN Las Vegas (December 23rd), Sheldon Adelson and the Raiders have a deal in place & the NFL is fine with it. The NFL, Raiders and the Sands group will have an announcement regarding that after the relocation papers are filed.
Lastly, my buddy and former Beast 980 talent Vincent Bonsignore (of the OC Register) has an excellent article on this (click to read) and how the NFL is willing to maneuver the TV deal.