I understand the L5R seemingly is an LCG that follows a different mold compared to other FFG LCGs. I also understand there's a possibility that a set rotation will be implemented in the future, as nebulous as it is. Just for comparison sake, what is/was the usable lifespan of each pack in the other LCGs? What is currently proposed in Netrunner or was proposed in Conquest?

Netrunner just underwent rotation. It's been out for 5 years. See also the FFG products page to get an idea of product volume.

So it seems that the packs cycles are usable for 3-3.5 years by my estimation, is this right?

Each arc is 6 packs. They also release deluxe box. Normally , each arc takes 6 months to release, and then they release a deluxe box (which is twice the cards @ twice the price) and then that takes up 2 months. Normally.

When the first pack of the 9th arc releases, then they phase out the first 2 arcs. Without deluxe boxes, that's a maximum of 4 years (with the packs that come out later being out less time, as much as a year) that a pack is out. Deluxe boxes add time to that equation, and I'm not sure that they are phased out - and if so, when.

I believe, that L5R is a typical LCG format game. I think they're just rushing the first six packs (well, 2nd-6th packs) to be out early for Tournaments. I expect that we'll then wait six months before any further releases. I could be wrong.

I'm hoping it would be 3+ years, which is conservative compared to other card games on the market. Despite the better price model, I have some friends that would hate something cycling out in less than 2 years.

It might be the same case here but anything can change at any time.

The rotation schedule is tied to releases, not time (because there isn't a precise schedule for releases). The rotation kicks in when there are 7 full cycles and a pack opens the next cycle (it's the same for every active non-coop LCG). At that point, the oldest 2 cycles are rotated out. If a pack was released every month, a pack would stay legal between 31 (a little over 2.5 years) and 42 months (3.5 years). Because of deluxes and delays, you can assume the actual durations will be longer.

@Duciris Deluxes aren't tied to cycles anymore (except in coop games where they still head the cycles): they come out when they're ready, and that can be faster than 1 every cycle (in AGoT2, the 4th deluxe is about to come out before the 3rd cycle begins). Also, deluxes don't rotate out.