I work in a glass shop (replace is our main source of business) and I would never depend on your jobs coming from the networks. You're much better off to spend some of your time hitting the agents (or hiring a fireball rep to do it for you) and ask them to refer business to you. That is where we get most of our insurance jobs. Anymore tho, with such high deductibles, list prices going down and price shopping by those cash customers, profits are not super great.
We are in a metro area, so we are an A shop, if you're in a rural area and could be a C or D shop, you might get more referrels and a higher profit margin.
Hiring a tech would probably not be a great way to break into the business IMO... workmans comp, fica, insurance etc etc. Your expenses would be so high just to get your foot in the door.
I would suggest OJT. Get a job with safelite for 6 months and let the train YOU how to do auto.
Having said all that, really, if you're in a big city, it's going to be hard for you to compete with the big guys.
There's a glass shop close to my home (I commute) that does locksmithing too, I have always thought that was a good combination. I once paid a guy $40 to unlock my door, took him 15 seconds and he said he learned to do it in a weekend.
I'd find something to partner with my business that has a much lower barrier to entry than replacement!