The only barrier to entry you can create is to consistently build a great product.

Do things that incumbents can't or won't do because it's economically or technically infeasible.

Modularize, don't customize. Build a platform as opposed to building all of the custom technology and custom vertical experiences.

What happens to the Microsofts, Oracles and IBMs of the world is that when they get big enough, they don't think they need to bring that same level of focus and energy to the end-user experience.

You can look at the cost structure of an incumbent company and discover: where are they not going to be able to drop their prices... because that business model is fundamental to the existence of the company.

Focus too much on the near-term and you won't get tomorrow's customers, focus too much on the long-term and you won't get today's.

In a user lead model, users are bringing in their own technology... and you can build software then, around the user.