Although the British monarchy is supported by a plurality of people across most age groups in Great Britain, it is among over 65 year-old's where the level is support is highest at 77 percent. Younger age groups are progressively more likely to oppose the monarchy, with 31 percent of 18-24 year old's opting instead for an elected head of state.

Houston we have a problem.  If 77% of the Royal support base is aged 65 or over, then in the space of 4 decades, that total will have shrunk considerably, and with less Royal supporters, decreasing with the younger age groups, there are insufficient people interested enough to match the numbers who will no longer be here to be part of the statistics they like to quote.  

5 out of the 7 Senior Royals recently named as the Main Senior Working Royals are above or near retirement age.  Does not bode well.  No Workforce or Succession Planning has been done, and look where we are now as a result.