Beneficent Retirement and Academic Successorships

In 'The Paradox of Beneficial Retirement', Saul Smilansky argues that "for a great many people, the best professional action that they can currently take is to leave their profession" (337) -- on grounds that they could reasonably expect to be replaced by someone better (!) -- and, moreover, that the personal costs they'd thereby incur (especially if eligible for a comfortable retirement) would be much smaller than the costs otherwise borne by the un- or under-employed.

In the academic case, I suspect that a similar conclusion may follow without the need for invidious comparisons.  Even supposing that one is above average in philosophical mettle, productivity, and so forth, so long as one has already enjoyed a long career in the discipline, it's likely that in most cases (not all, of course!) one's most valuable contributions have already been made, and the discipline would benefit more from hearing new voices.  (This seems especially likely given the hyper-competitiveness of the job market in recent years: we all know that there's an immense amount of philosophical talent out there, struggling to secure stable academic employment.) 



Suppose that over a 100-year period, a single tenure line could either be filled by two individuals (for 50 years each), or three (for 33 years each).  In the vast majority of cases, the latter strikes me as very obviously the preferable arrangement, for both human welfare and the discipline of philosophy. (Exceptions for superstars like Derek Parfit: if only he could have been with us longer!)  But in fact this underestimates the gains from shorter careers: senior professors have much higher salaries, so greater generational turnover would save a lot of money and hence enable (e.g.) additional post-doctoral positions to be offered alongside the tenure line, at no additional cost to the university.

Note that this is nothing to do with age per se: someone of advanced age may nonetheless be a newcomer to the discipline, and someone merely middle-aged may already have had a long academic career. There are obvious reasons why age and career stage tend to correlate, but it really is the latter that I'm addressing here.  (Though age may make a difference to one's eligibility for retirement benefits, and so be relevant in this respect to assessing the costs of non-employment.  Younger folks are likely to be more financially vulnerable.)

In light of this, I think that tenure probably ought to be time-limited, e.g. to 25 years, at least if this could be done without risking a 'slippery slope' to eroding tenure altogether.  In the meantime, more should be done to honour and encourage retirement (so long as the university guarantees replacement!).  For example, just as we honour donors by naming endowed chairs after them, so we could name the new "Joseph T. Bloggs Assistant Professorship of Philosophy" after the newly-emeritus Prof. Bloggs, whose generous decision to retire is what enabled the new job search to go ahead.  If a potentially-emeritus professor wishes to remain involved in department life, more ways could be found to accommodate this desire (without requiring that they remain on the university's payroll).  They could even serve as a kind of informal mentor to their academic "successor", if they so wished.

Any other suggestions?