If ANT does the price hike, OAI will be forced to backtrack because they're just not equal, OAI is behind. ANT would still be a much better value overall, and people will remember that it was OAI that made their ANT subscription more expensive. So the hiatus will happen. There's a lot of users that have $200 plans on both ANT and OAI. $500 leaves the slot for just 1 sub for them.
But I think the price hike is not going to happen. $500 is much, much harder to justify than $200 for the same usage. This is a horrible business decision, so Anthropic may just watch OAI bleed customers.