It's very difficult to find out precisely which cells these Chinese packs use, but I've found three general types, of which only two are in common use. The YESA packs seem to be made up from 10Ah cells that are rectangular, with screw terminals, but I have a strong suspicion that inside these rectangular packs there are some pouch-type cells connected in parallel. The Ping packs (and the other "duct tape" packs) mostly seem to use the 5Ah pouch-type cells, connected up in parallel to give 10, 15, 20 Ah etc.
I have found some different shape pouch cells, which are 6Ah capacity, that I believe are used in those packs that are advertised as 12Ah.
It's far too early to tell what the life of these cells will be, but I doubt that cycle life will be the determining factor. I would imagine that ageing will reduce the cells capacity way before cycle degradation, at least for those who only charge a pack every day or two. If I had to guess, I'd say that the life of a well-cared for LiFePO4 battery should be two or three years, which seems reasonable.
It's quite possible that the useful life of a LiFePO4 pack could stretch out beyond this, but this is still very good when compared with SLA batteries. SLAs struggle to get more than a few hundred cycles, or a couple of years, of useful life, less if they are repeatedly allowed to discharge close to their lower limit. NiMH has the edge for overall longevity, I suspect, but at the expense of added weight and lower capacity, plus their rather nasty self-discharge trait. I went for a month without using my bike a while ago and the battery appeared to be at exactly the same state of charge as it was when I left it. A NiMH pack would have lost a fair bit of charge over the same period, I'm sure.
Jeremy