I'm highly interested in this as well. I've been playing around with this for over a year.
I haven't really found any concrete answers, but I have been doing some testing and so far, I'm pleased.
I think this will work, if it's done properly....but that's the big question tho: What's proper?
Not sure if this is the "right" way or not, but here's what I've been doing.
I've got a vacuum sealer that works with mason jars. I loosely pack some product in the jars after they've been cured and dried, then vacuum seal them and then I've set them aside for a increasing amounts of time. So far, the longest has been about 8 months or so, but I didn't track the date, so it's at best an arms length estimate of time. When I opened that one up, it was just fine. No visible signs of any degradation, or mold/mildew (at least not that I could tell with a 60x loupe). It smoked just as good as it was fresh, but I didn't have anything to compare it to at the time. I couldn't tell it from any other, though. Seemed perfectly fine.
So, that set me off on a quest. This time I was more "scientific" in my approach.
What I did for this test was to track the date of packing. 7 months and 19 days ago, I sealed a good bit up. My plan is to take it to at least 18 months, perhaps two years. I put a note on my calendar 18 months out to remind me. I can't actually see it in the jar, though, as I protected it from light this time. I put it in the basement where it won't be disturbed and it will remain relatively cool year round. I don't have a lot of moisture in my basement, so I thought that was a good place to put it and forget it.
To block the light out, I took a standard mason jars and cleaned it really good, then used some flat black spray paint and paint the OUTSIDE of the jar, NOT the inside. I used masking tape to protect the screw part of the jar, where the ring will hold the lid down, so that it has a good surface to hold on to.
I let that dry for a few days. I then ran it through the dishwasher, then hand wash it again to make sure there's no soapy reside on the inside nor any paint smell. I let that dry completely, then packed it loosely full with about an inch of space from the top of the jar. I put the lid on it, and vacuumed out the jar as I would normally do. Actually the machine will run until it can't vacuum any more out, then shuts off and it's sealed tight. You have to use the edge of a knife to open the lid from the vacuumed jar, so it's a good seal. I put the band on it nice and snug, then put the jar away and forgot about it until I saw your post and I looked at my calendar to see when I stored it.
You might think "why go to all this trouble?" Well, I'm somewhat a casual smoker. I may only smoke two times a week, four at most. I grow one plant that provides me more than I can smoke in a year, and don't want to let it go bad on the shelf. So my plans would be (if this works) to grow it, then portion it out in a month or so quantities, and seal them up. I'll have a jar for each month, or perhaps each season, and I'll just use it like that. I figure as I get to the last few months, i'll start a grow again, and repeat the process.
If anyone knows of a reason why this won't work, I'd LOVE to hear from you on your thought