Life of a rambling rose

American Pillar been growing for about 40 years, maybe longer.  It's covered in mildew, it grows through a laurel hedg.  I am tempted to take it out, I am not keen on spraying.  But I wondered just how long ramblers last for..

a friend end has lost her Rambling Rector and it was quite a long time in situ.

any body have suggestions