You can create unlimited multi site WordPress networks and have unlimited clients purchasing your WaaS services.
We don't limit the WaaS license on the number of networks but on the number of domains.
You can have unlimited networks and installs but on 1 domain. For example you can create different WordPress multi site networks on different subdomains for different niches of your WaaS. As long as you are on the same domain you can have as many networks as you want.