Princeton just did a unilateral disarmament, and in terms of competition, the other colleges are best served with the status quo.
If that happens, Harvard benefits a great deal in terms of getting a really strong EA application pool. Yale, Stanford, and MIT see a smaller increase in EA applications relative to Harvard’s increase. Columbia might see a small ED uptick as well, and those acceptances are binding.
So even before Princeton gets its RD apps, many of its strongest potential applicants might have already mentally committed elsewhere. Every one of its competitors benefits at Princeton’s expense.