Network effects usually destroy or marginalized competition until they themselves start stagnating decaying. Sometimes they produce partially-overlapping duopolies, but maintain their monopoly-like power.

Facebook marginalized linkedin and sent twitter into a niche.

Internet Explorer and Windows destroyed competition, for a long while.

Google Search marginalized everyone for over 20 years.

These are multi-trillion-dollar businesses. If OpenAI creates a network effect of some sort they can join the league.