How would you expand a lead gen agency that only does PPC currently?

I'm getting clients finally in a very specific niche and super enthused that I finally have something that scales. Obviously I could expand by getting more. I have also thought about opening up a teaching wing of the business to sell box products and maybe upsell into coaching or turnkey (turnkey being exactly what I focus on now).

But what I'd really like to do is entrench my position in this niche. All I do is generate Facebook leads for businesses that offer a free class, think something like yoga or martial arts. If I could find new channels to generate leads from, then my business not only becomes more profitable but develops a deeper connection to the clients (since we can generate even more business for them) and most importantly, is able to survive a catastrophe like FB lead costs becoming unprofitable.

The one catch is I must be able to manage everything remotely.

Has anyone walked this path? I'm thinking of expanding into EDDM and maybe Valpack, would love feedback on whether these are good next steps or if I should branch out online first.