Why would Red Bull want to let Webber go.
1. He wants to leave because there is a better offer. They don't come any better than driving a Ferrari.
Red Bull will let him go because they had an understanding with someone a while back, promising that driver a race seat for 2011, Kimi Raikkonen.
Red Bull want to secure their future and know a very talented driver will be available at the end of 2010, Robert Kubica. They want to have some one in place for when Vettel leaves.
Kubica, will or rather should leave Renault at the end of 2010. It's only Renault in name, 75% of the team has been sold off. Renault wants to concentrate on the engine side again. This car was built with their resources, mistakes from front runners this year, reliability problems and excellent driving by Kubica has the team where it is right now. This team might be like the Brawn/ Mercedes of 2011. Not the same budget, resources and people to help them develop especially with a new tire manufacturer coming in and Kubica is too good to waste time at a team hopping it would become a front runner. An offer from Red Bull or Ferrari would pretty much guarantee a front running team.
The key to driver market might be Ferrari and not Webber. They seem to be holding more cards than him, and pretty good ones at that. They decide whether Massa is worth keeping anymore, they are also rumored to have an option on Kubica for 2011, which they have to take up by 15th July. The coming few races, especially the next one will be important for both Massa and Webber. Massa always goes very well in Turkey, and so does Vettel. Should Vettel beat Webber, people will forget about his back to back wins, and talk about the chassis Vettel had and the problem that was discovered with it etc and point to that as reason why he was beaten by Webber.
Massa has the test of his life. He is some what of a specialist around Istanbul Park. At the start of the season i thought, Alonso would destroy him much as he has but expected qualifying to be a close run affair. That has not been the case. He needs to turn his season around, not just to keep his hopes of staying at Ferrari alive but also help him get a competitive drive for 2011, should Ferrari decide to replace him. I don't think he will drive for Nicolas Todt, if he got an entry into F1 next season. Maybe what ever remains of Renault, would be an option.
My feeling is, the die has been cast. Ferrari will not do anything to destabilize their team and their team leader. They felt obliged to give Massa the drive this year because it would have been a PR disaster had they sacked him while he was recovering from his injury. The comments he made during that time were in bad taste and he probably thought he would handle Alonso much in the same way he handled Raikkonen. It's not worked out for him. From marketing point of view, it makes perfect sense to keep him at Ferrari, and with drivers like him that's usually the deciding factor but he might prove to be an exception to the rule.