If they would be profitable without further spending on R&D they would stop spending, but as you say they are in an R&D race so they can't stop and thus the hypothetical is irrelevant.

For how long? If OpenAI or Google (or Chinese companies) decide to keep losing money longer than them they'll pass them pretty soon.

The AI race is going to be won by whoever has enough money to burn to outlast competitors and I'm increasingly skeptical that's going to be Anthropic