With immediate effect. Now that is a shock.

Dear Toto,

I see a vacancy has arisen....

http://www.bbc.co.uk/sport/formula1/38185846

Who gets the drive then?

Rosberg unexpectedly retires, Jension unexpectedly unretires.

I think Vettel is going to drive for Mercedes

Vettel would be my guess as he's not happy at Ferrari.
Don't think Alonso can get out of his contract and I'm not sure if Hamilton would want him there!

It would be great to see Hamilton and Vettel in the same car but I don't think either of them would want to be in the same team.

Bottas seems to be the most likely choice.

Bring back Jenson!

Yea!

Rosberg's decision has increased my respect for him. I have hugely admired his ability to come back from being obliterated by Hamilton with performances that have shown outstanding resilience and mental strength. I used to suspect that he was a pretty makeweight in F1 only thanks to his father, but it's not a view I hold any more.
To retire now - as Champion - must surely be a great choice if he has no more questions to answer to himself.
Bravo!

As for his replacement, Mercedes will have to balance a couple of factors:
- the need to maximise success now while their car is the class of the field
- the desire to bring on a young driver to keep Mercedes at the front after the Hamilton/Vettel/Alonso era has drawn to a close.
- image: Mercedes need to combine talent, prestige, boldness and success.

There's only one driver I can see out there who answers all those criteria - and who the entire world would want to see up against Hamilton in equal machines - but I can't imagine how much Red Bull would demand to release him.

Ruling out Verstappen would leave:

- Vettel (don't think Lauda/Wolff would get on with his style of petulance, as opposed to Hamilton's),
- Ricciardo (I suspect loyal to Red Bull and - although probably as talented - nowhere near as eye-catching as his team-mate),
- Button (nope. Just not going to work; Button has clearly made the decision to quit - as shown by his recent performances)
- Wehrlein (most likely of the young guns - Merc young driver and looks easily capable in F1, despite uncompetitive car)
- Ocon (Wehrlein light)
- Bottas (left-field choice. Williams unlikely to let him go, not terribly charismatic for the Merc brand).
Alonso (Most likely of the Big Hitters. Still viewed as the F1 drivers' driver, the ticking clock could persuade him to make it happen, McLaren be damned. Ron Dennis' departure could mean the desire to keep him at Woking could be diminished. Reuniting Alonso with Hamilton would be superb box office and I'd put my shirt on the Spaniard being competitive right away).

Blimey, did I just say all that? F1 might be interesting again!

I'd like to see Alonso in the seat for the reasons you cite. But I don't know how likely it is to happen.

I had read that Williams might be perusuaded to let Bottas leave if Toto offers them a good deal with regard to engines and cash (the insinuation was that Williams weren't as well off as we might think).

Some interesting views.

I would love Hamilton/Vettel or Hamilton/Alonso. Light the blue touchpaper and stand back a distance.

Given the Rule changes and the lessened importance (relatively) on engines and Red Bull could again be the place to be. SO can't see their drivers going anywhere.

Valentino Rossi maybe?

If Alonso moves, would Button be asked back to cover his seat? Else McLaren would be very light on experience.

Did anyone else spot the difference in size for next years wheels, the rears look huge!

Given the speculation, Button has been surprisingly quiet...

I can't see Button making a U-turn and I don't think the Red Bull drivers will be going anywhere either as the Red Bull car is expected to be a potential challenger next season. I would love to see Alonso taking the fight to Hamilton in the Mercedes but he may be a little pricey, Bottas would be solid choice but a clear number two driver to Hamilton. I expect Wehrlein to get the nod if I'm honest but wouldn't be too surprised at a complete left-wing appointment either.

I reckon Button is out on the lash and not thinking about F1 at all

Reading the F1 news on motrosport.com I think Mercedes really want Alonso but will take Wehrlein to avoid a contract battle with Mclaren.

It has put Mercedes in a bit of a pickle. Everyone is pretty much committed but I expect they've all been on to their agents asking about the 'get out' clauses in their contracts.

There's nothing to guarantee another dominant season from Mercedes, so switching from McLaren, Ferrari or Red Bull perhaps isn't the dream ticket it might have been last year.

Safe and easy option is Wehrlein but we'll just have to wait and see where it lands.

Don't forget Williams run Merc engines, so the Bottas deal is a lot easy to engineer than from another team.

Can't see Hamilton being overly impressed with having Alonso next door again, and I reckon (like Button) his best days are (a looooong loooong way) behind him.

Get the feeling Vettel is trying to go down the Schumacher route of trying to re-energise Ferrari all on his own.

Wehrlein or Bottas I reckon.....or someone left field from GP2 we've never heard of!

What is the betting that if Alonso leaves McLaren they have a great car next season. He does seem to have had the ability to be in the wrong car recently. Would be great to see him in the same team as Hamilton again though, but not sure Mercedes want to spend as much as it would take to get him out of his contract.

Bottas is probably the best bet, with Wehrlien going to Williams and a reduction in their engine supply charges for 2017.

Toto is said to be a Bottas fan, but that would leave Williams with no real experience or continuity in the car. Which could, potentially, cost them much much more than any engine deal.

I think Toto is more than a fan - I believe he's Bottas' manager. I've always wondered how that conflict of interest is resolved when a team principal is also a driver manager. I don't think it's that unusual.

I wonder how much williams' engine contract negotiation included having Totos' wife as their reserve driver?

F1 is full of conflicts of interest (or leverage depending on how you see it)