Toro Rosso, co-owned by Red Bull energy drink billionaire Dietrich Mateschitz, have a guaranteed budget for 2009 but their future remains uncertain.
Red Bull Technology design the cars for both Toro Rosso and Red Bull Racing but in 2010 each team will be required to design and make their own, a huge burden for the smaller, Italy-based outfit.
"I would struggle to carry on alone," said Toro Rosso co-owner Gerhard Berger. "I need the backing of a car manufacturer which isn't there."
Red Bull use their two teams to promote and sell their product while Force India are bankrolled by aviation and drinks billionaire Vijay Mallya, who says he is in for the long haul.
Williams, the only team without a manufacturer or billionaire behind them, this week reported losses of £21.4million for 2007 but their chief executive claims they are well-funded for the future.
However, he thinks big-spending manufacturer teams may be more vulnerable. "It's a lot of money that can be addressed with one swish of the red pen," admitted Parr.
BMW, Fiat (Ferrari), Honda, Mercedes (McLaren), Renault and Toyota all either wholly or part-own teams, some with budgets of more than £200m a year, against a backdrop of dwindling sales and sinking share prices.
"Those teams that are very dependent on car manufacturers for funding and don't have commercial sponsors might be under more pressure," said former Benetton and BAR team boss David Richards.
"But there is unlikely to be any knee-jerk reaction. It [withdrawal] is such a high-profile decision to make."
To try to bring down the costs, the teams have formed an association to work with the FIA and commercial rights holders.
"I think it is absolutely urgent," Parr said. "Whatever measures we take must be in place for 2010. Anything beyond that is too late, both the teams and the FIA recognise that.
"The car manufacturers could halve their spending in F1 tomorrow. I know that because I know what we are spending. Some teams could save millions."
On the plus side, the money is pouring in from new venues such as Singapore and Abu Dhabi, which will make its debut next year, and there is no immediate sign of sponsors running for cover.
"I think we had 900 guests over the Singapore weekend. Our sponsors were enormously active," said Parr.
"Businesses still have to achieve their key objective and Formula One is still a unique platform for doing that."
