And there have been plenty of instances in NBA history where teams have been able to rebuild much quicker than 8 years; make the conference finals, NBA Finals, win championships. Given the economics and avenues available for teams to improve, it shouldn't take close to a decade.
Sure. Can you really
plan to have it work out quicker than that?
I agree that going to your fans and saying, "Hey, we have a plan to be good in 8-10 years!" sounds horrible, and it should.
My point is that I think a good GM should have a plan in place that accounts for as many variables as possible. Meaning that if everything goes right, maybe you get right back to competing at the highest level within a few seasons, but if things don't go your way, you still have a long term plan that you expect to get you on track within 7-8 years or so.
The idea being that even when things don't go your way, you remain disciplined and patient because you have that long term, big picture plan.
You don't make rash decisions like firing the coach or the GM, or radically altering your roster and spending money in free agency, just because things aren't going the way you hoped.
All of that means that I don't think it's so outrageous to say you have an "8 year plan." If your plan REQUIRES 8 or more years just for your team to become decent enough that your fans will actually want to watch, then yes, that's indefensible.