I noticed Mr. Eaton's obituary last week in the Toronto papers:  a short notice without comment or photograph.    But  20  years ago his death would have been front page news.   Time has erased the Eaton dynasty, once such an influence in Canadian culture,   and I wonder how many readers younger than 30 even know of the family or  connect Mr. Eaton with the Eaton Centre, for example, the last remaining symbol of their wealth and power.   The mortal coil indeed...