It seems its not about the reduced expenditure, unlike the media has said. Its more about having a 2 tier system were unless you are capped basically you wont be able to keep up with the capped cars.
From what I can gather the rules for capped teams can allow them to use flexible rear wings (big gain in speed and cornering), higher KERS boost, higher revving engines, freedom for testing, although they reckon cost for cost the wind tunnel is nearly as good.
Flavio also said that FOTA had come up with a plan to reduce costs between now and 2012 at a rate the teams agreed on, but the Max and Bernie have ignored this and just introduced their system without any consultation with the teams.
If you was a team princicple and knew that you wouldnt be able to get into the capped scene before 2012, therefore knew you wouldnt be competing you would also pull out.
Im not a Ferrari fan but still think F1 wouldnt be the same without them. If Renault Ferrari Redbull which would mean Torro Rosso and Toyota pull out thats 5 teams, BMW may follow and I cant see Maclaren getting in the cap so you could have 7 teams pull out, if they get 3 new teams we could have a 12 car grid

Bernie would have to pay millions back to TV rights who have signed for a 20 car grid, sponsors would drift away and F1 would not be here.