The doc mention about the 3Scale Wildcard Router as a solution to doesn't create a gateway for each service, but doesn't provide any details about it.

https://access.redhat.com/documentation/en-us/red_hat_3scale/2.3/html/deployment_options/apicast-openshift

On the last paragraph:

"Create a new route for every 3scale service you define. Alternatively, you could avoid having to create a new route for every 3scale service you define by deploying a wildcard router."