Lewis Hamilton will leave McLaren at the end of the season to drive for Mercedes in what is arguably the biggest shake-up of the driver market for over a decade.
The knock-on effects will be huge, and felt all the way down the pitlane. Sergio Perez has been announced as Hamilton's replacement at McLaren, Sauber have a vacancy (and not just for a driver), Ferrari have lost a young talent and Michael Schumacher could be facing up to a second retirement.
Let's see who is affected the most by this, and how.
Lewis Hamilton's departure leaves McLaren without a top-drawer driver for the first time in many years.
The last time they were without a driver I'd rank inside the sport's top three was 2002—Kimi Raikkonen's first with the team, when he was still learning his trade.
Since then, they've had Raikkonen (the improved version), Fernando Alonso and Hamilton. At least one of the three was there every year up to the end of 2012.
Jenson Button is a good driver, but he can't make a difference the way the very top drivers can. Unless Sergio Perez turns out to be a true superstar (and that is very much up in the air), McLaren could find themselves struggling in 2013—and perhaps further into the future.
And that's just on the driving front. Losing a man who is (partly by virtue of his many celebrity connections) one of few real global superstars Formula 1 has could see their finances and sponsorship arrangements taking a substantial hit.
All is not well in Woking.
Lewis Hamilton's arrival at Mercedes will almost certainly mean the end of Michael Schumacher's second career in Formula 1.
The German has put in some impressive performances in 2012, but has also made several "rookie" mistakes. Twice he has crashed heavily into rivals—Bruno Senna in Spain and Jean-Eric Vergne in Singapore—after misjudging braking zones.
Even his most ardent supporter would admit that the two errors were something the "old" Michael would never have done.
Schumacher says he has not yet decided whether he wishes to drive next season—but there are few options available.
Replacing Perez at Sauber looks the most likely move, but even that is an outside bet—and would Michael really join a perennial midfielder?
Probably not. It looks like the Brazilian Grand Prix in November will be the final race for the most successful driver in the history of F1.
A glance at Sauber's livery reveals a very strong link to the Latin American market.
The world's richest man, Mexico's Carlos Slim, has placed two of his companies' logos on the Swiss cars —Claro and Telmex. Also present are Cuervo Tequila, Disensa, NEC, Interproteccion and what appears to be the Mexican tourist board (Visit Mexico).
It requires no great skills of deduction to conclude that Sauber is so heavily endorsed by such companies due to the presence within the team of a Mexican driver.
Now he's leaving, what happens to those sponsorship deals?
Unless they promote Esteban Gutierrez from the reserve driver slot, some of them will certainly withdraw their backing.
And if that happens, the funding shortfall is likely to be significant. Sauber's driver choice for 2013 may well be out of their hands.
Sergio Perez was a member of the Ferrari young driver academy, and many tipped him to be a future driver for the Italian team. His Ferrari connection was okay while he was at Sauber.
But it seems unlikely that Perez and Ferrari could remain linked during a spell at one of the other big teams. His multi-year deal with McLaren appears to end that relationship—for now at least.
It won't affect Ferrari's plans for next year. The probability of Perez replacing Felipe Massa for 2013 had become so slim it might as well have not existed. And in 2014, rumours suggest Ferrari have a very strong line-up arranged.
So Ferrari probably won't be affected at all—unless Perez turns out to be a genuine superstar. That's the big risk.
And if it happens, the Mugello-based outfit will have plenty of reasons to kick themselves.
Paul di Resta has a long association with Mercedes, having driven for the German manufacturer in DTM for several years before arriving in Formula 1.
Whenever replacements for Michael Schumacher (if he did choose to retire at the end of 2012) were discussed, di Resta's name was always one of the first mentioned.
That option has now been taken away.
Mercedes are a German team and having at least one German driver appears to be quite important to them for marketing purposes in their homeland. While Hamilton is with them (at least three years) it's highly unlikely di Resta will even be considered.
The Scot's future now seems to lie elsewhere.
Of course, Mercedes are the big winners. For the first time since 1955 they have a driver considered among the very best in the sport. After three years of mediocrity, it's finally time for the German manufacturer to shine.
Hamilton's arrival is a statement of real intent. It tells the world that Mercedes are committed to Formula 1, and that they're willing to part with large sums of money to succeed.
For all his greatness in his younger years, Michael Schumacher was never going to lead Mercedes to the next level. Nor was Nico Rosberg.
Hamilton can. The presence of a top driver will inspire the team to push even harder to achieve their goals, safe in the knowledge that if they can deliver, he will too.
And if they can't succeed together?
Well, it'll let Mercedes know that maybe, just maybe, F1 isn't their thing.