Healthcare bosses are "confident" they will have the money to expand existing services should St Helier Hospital lose its vital services.
Last week the Better Services Better Value (BSBV) put forward its preferred model for the future shape of health services in south west London recommending that St Helier lose its accident and emergency and maternity departments.
Under its recommendations St Helier will retain a stand-alone urgent care centre which could treat up to half of current A&E patients.
It has also proposed a planned care centre at St Helier Hospital for non-emergency surgery for patients across south west London and said they plan to deliver more services in GP surgeries and people's homes.
Services at Kingston, Croydon and St Georges will be "expanded" at a cost of more than £100m in a bid to save an extra £15.9m per year.
To fund the expansion, St Georges will have to find an additional £69m, Croydon £40.1 and Kingston £5.5m.
Dr Howard Freeman, a Merton GP and joint medical director for BSBV said: "We are fairly confident that the money will be made available to us from the Department of Health.
"Despite what people might think the NHS is an integrated care service. "We would not be going out to public consultation if we werent confident we had it."
Dr Freeman admitted wards were already "crowded" but said he was convinced there was sufficient space to expand.
He said: "Theres going to be changes on all the sites and in the community and there will be a fair amount of services moving around.
"We have been assured that there is space to deliver these services on these sites.
"All the hospitals will continue to expand in different ways."
If approved by the joint boards on September 27, the plans will go forward for a three month public consultation on October 1.