There is no "moving into the market", because as soon as a market consolidates around one or $very_small_number of players, cost of entry and market capture make competition impossible. So competition ends.
This is where we are now with tech. It's basically impossible for anyone new to compete with Amazon, Google, Facebook, etc. It's also where we are with established players in other sectors such as Airbus.
The only two things that can break the logjam are government action to split up monopolists, and the invention of a new market space with a viably low cost of entry.