In practice this could work if done properly. Most other countries in the world have their ambulance and fire service combined.I understand the paramedics being sceptical and that the two services have seperate cultures. But there could be advantages for both fire crews and ambo crews. You could get firecrews to help in busy times (they do this anyway) and help give ambo crews a rest, they could share stations, experience and you might get less false alarms particular when a fire engine turns up to someone simply wanting a lift back home after a heavy night on the lash.
The yanks have firefighter paramedics (their paramedics arent as highly tained as ours though) who depending on the rota may man an ambulance one shift, then man the fire pump on the next. In the UK I would share the costs but wouldnt share the competences, keep paras and EMTs seperate to firefighters but operate them under the same organisation. You cant turn round to existing paramedics and ask them to train as a firefighter and vice versa. But maybe you can with new recuits if the services are combined ?