Yes, you are right. After a few good cases will come another ones. This will earn credibility. Besides as was mentioned above, no one has to take their word on anything. That's business and there are agreements there. Official agreements will ensure that two parties will do as conditions tell them to do. If someone breaches a clause, they will suffer consequences.
The most difficult thing is to get the first serious customers. And also to show that the projects have already been implemented and they work without problems.