Dje,
While I don't presume to know what Patek "needs" and am fuzzy on any true relationship that may exist between age and taste, I certainly agree with you that the Calatrava line lacks models that have the appeal of the 5960. The 6000 may come closest among existing models to filling the niche you describe.
Your proposal might require using a calber other than those currently used in the Calatrava line, as I suppose the case would need to be 38-41 mm to have broad appeal to this audience.
Are the new Annual Calendars, albeit at a higher price point, more in the style you envision?
What would you think of an enlarged version of the 5107 configuration with a blue dial and lume? (I might go for that, and I'm only young at heart.)
Park