i just got a juniper bonsai tree and it looks fairly young maybe 2-3 years.
anyhow, i'm wondering how long can i expect this to live? lets say i were to
care for it and repot, water, give good sunshine, feed and everything else
expected of a good master...

If you are keeping it indoors, about a week.

Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)