If the entry requirements are the same, then there will be few older career changers at those “Ivy League and other top colleges” compared to the number who will go to other colleges, simply because most will not get admitted to “Ivy League and other top colleges”.
Now, if the “Ivy League and other top colleges” greatly increase the volume of students educated through distance education, then there may be the effect you suggest. To the extent that B above is something unique about them, that could be better. But they would dilute C above by becoming less exclusive, so they may not want to do that to a large extent. Of course, if they did do such a thing, that may be trouble for other colleges that are less attractive in terms of B and C.