You can already see this in the numbers of AKs Arsenal has imported to K-Var recently, with popular models not being as available. Granted they have always ebbed and flowed but the ebbs are getting longer. Another example is Triangle or Polymer side folders. These have sharply risen in prices as availability has gone down. Parts kits that were once plentiful are now drying up and the ATF change on kit's barrel policy have overall made them less attractive as well. Even ComBloc metal 7.62x39 magazines are getting spotty at retailers. The U.S. made aftermarket will be there to pick up the slack, but the price point for the same amount of quality will go up.
Going back to the specific issue of AK74 magazines, hopefully US Palm or even Suarez's TSD will get on board. For a long time, high-end U.S. made AK74 magazines have been seen as economically soft products due to the problem of a more niche market and the availability of cheap, high quality surplus magazines. But it seems that may have finally shifted now since the surplus magazines are not in stock at most retailers. US Palm has a great AK30 magazine that hopefully could be easily redesigned for 5.45x39. TSD is a potential too since it has an AR15 magazine that might be adapted. K-Var does import new production Bulgarian magazines but again this seems to be never imported in large enough numbers. Maybe even MD Arms will finally bring their Quad Stack to market and be in 5.45x39 as well. Tapco's magazine may be a good option if you are okay with going down a notch from surplus quality. I know their magazine design and Tapco in general has a lot of fans and detractors, but no matter what your opinion of the company, you can't deny that Tapco magazines are at least slightly lower quality due to their lack of metal reinforced lugs/feedlips/floorplate rails. Hold on, it is going to get interesting!