Some people do get fired based on age. Sometimes it is even completely legal, even in places that are not "right to work". For example, in Canada, high court cases have ruled that age-based mandatory retirement of university professors is legal.
With respect to "bottom line", what has to be calculated is not just "Are you more productive / better at producing ideas than recent grads", but "Are you more productive / better at producing ideas than as many recent grads together as could be bought with the higher salary you are being paid?".
(If your company happens to be contracting out work to India and the like for cost reasons, then you should certainly expect that you too are being examined on a "What could we get for that money?" basis.)