Problem with that is that it's a fair bit different nowadays when compared with the 90's with Benetton, McLaren and Ferrari driver systems.
With team orders banned it's very feasible for Webber to say sod it and just do his best to win, RBR can either fire him or take steps during races (or more specifically pit stops) to coerce the result, which I'm not sure the FIA would look too kindly upon...
The number 1/2 driver system does work, but only when the 2nd driver accepts to be a second driver, or they're slow enough that they're the second driver by default. Webber didn't accept (and from his actions at Silverstone Won't accept) being a number 2 driver, and there's not much RBR can do about it.
I do think Webber will be trying to get out of his contract, although other drive options are limited it's quite obvious that the only way he'll win a title at RBR is by fighting against his own team, somewhere like Renault would probably happily take him to go alongside Kubica, doubt he's more likely to win the title there but he can't exactly be less likely to win it...