In a season of huge controversy I don't think the FIA is going to add further fuel to the fire. At most he will get a fine and even then, I think it will be Mercedes that get it as a team rather than individual ones for Toto and Lewis. But I don't think that will even happen, if everything being said is true then Lewis could just say he didn't come for health related reasons (mental health) and the FIA would be suicidal to argue/penalise.
The FIA are very aware they need to get their own house in order first, as I said before, Masi should really consider resigning after the absolute shit show of Abu Dhabi. The FIA launching a formal review into the last race with a view to tighten up the rules and provide the teams/drivers with more clarity is as close to an admission of guilt as you can get without actually admitting Masi screwed up.
A lot of people are confusing Masi's decision to rewrite the rule book with Max not deserving to be world champion. No-one (apart from a small few) is saying Max didn't perform a World Championship winning drive this season, both drivers and teams gave it everything. The crux of it is that, Masi effectively decided who was going to win the championship by changing the way in which the rules are interpreted on the closing laps of one of the closest fought seasons in the history of the sport.
Whilst I am ranting, all the people critising Perez for poor sportsmanship are just bitter, I would expect every team in the same position to do the same thing as this is a TEAM sport. I am a Hamilton supporter through and through, and I would have expected Mercedes to have done the same thing had the tables been reversed and for Red Bull to be the ones lodging complaints how the rules weren't followed and snubbing Gala's. Teams will always fight their corner whether they believe they are in the right or not.