It is scalable as long as you are not the bottleneck. For example, if you are the only one meeting with clients and drawing up contracts, you will find yourself stretched pretty thin doing that. Imagine 50 clients all asking for status updates at the same time.
I would explore the possibility of standardizing your services and prices, and making it a self-serve model so clients can sign up and manage their projects through an app or website. Then you can free yourself up to just do marketing.