You have to blend everything in Astrology.
Saturn retrograde invites more introspection and inner work. Regarding the 8th house, this could indicate reflections on issues such as death, shared finances and deep transformations.
There could be karmic issues related to affairs governed by this house, such as debt and/or sexuality. You might face fears and traumas from the past.
Retrograde being inwardly directed, this could indicate a cautious and serious attitude, with a tendency to think deeply before making a decision (in transits, a retrograde planet may indicate a temporary period of reflection or delay, while in the birth chart, on the other hand, this indicates a lasting quality in the person's life and personality).
In the sign of Taurus, you might develop a strong need for stability and economic security (the 8th house also is the second of the 7th). Since Taurus is a fixed sign, these transformations could be slow and demanding.
Harmonious aspects with planets, such as the trine you mentioned, can make this transit less tough, leading to more structured and well-planned growth. To get a more accurate prediction, one would have to see the other planets, the transits they form, etc.
Some websites say it being in the sign of Taurus here gives one a shortened life instead of longevity?
Considering Saturn's disciplined nature and the physical endurance associated with the fixed sign of Taurus, I would say this position tends toward longevity.
Also from Azazel's Astrology:
"Saturn in the eight can give a long life, with one dying from natural causes." 
