Your users do not have a point at which their demand for software is saturated, any more than they have a point at which their demand for products is saturated. Your software solves a need or a want for them. Needs or wants are essentially infinite. (We live lives of ridiculous abundance compared to 99.999% of all humans who ever lived, and yet we still don't have enough. Whether that is just a statement of fact or indictment of consumerist society is up to you.)
Nobody looking for bingo cards for mom's birthday party says "Hold on, wait a minute -- do I need a widget for this, or a suite?" Nor does playing the software taxonomy game help me sell a single copy to any customer anywhere.
As to the question of how many paying customers you need to make a go of things, that question actually matters, but forget about the impact of widgets. I'm going full time with about 1,000 sales a year, which puts me more than ramen profitable at my price point ($30) and cost structure. That is not a one-size-fits-all answer: if you have multiple founders to support, have a wife and kids in San Fransisco, etc, you might need more. If on the other hand, you're billing customers $20 a month, you need rather less.