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I had never considered this, but the discussion at Guild Wars 2 Forum: Bags brought up the fact that bags are pretty common within PvP chests. The natural supply of bags is starting to look a little too large for my liking. Let's see, you can get bags from PvP chests, mob drops, 3 professions out of 8, etc.
Will bags still be a great money maker? Yes, but like everything else I would recommend not putting all of your eggs into one basket. You've also got to consider that maybe lower level bags drop like candy on purpose, then later on perhaps they become far rarer, as well as the materials used to make them.
Bags could be a great money maker, but as I suggested in that thread, focus on stockpiling the materials instead of actual bags themselves. You can always just hit craft 100 bags and watch as they get created faster than bullets out of a machine gun thanks to the way Guild Wars 2 handles mass crafting.
Early on, sell what bags you can, but only create a few to list then hold on to the rest as raw materials.