This was just announced this year @ Shot Show...
My guess is, it will be several months before the distributors see them, then another month or so before they are in gun stores....
I don't think this will be an easy "sell" for the local gun stores....
Currently, you're local shop will have maybe 1 or 2 Mossberg stocks and maybe one forearm in stock. In order to be able to "demonstrate" the advantages of the "FLEX" system, they're going to have to carry more than one of the FLEX stocks & a couple of the FLEX forearms... You're asking the gun stores to carry parts that nobody has asked for....
I can see some of the national "chains" like Dick's, Cabelas, Gander, etc. carrying these but for the local shop, it's a big nut to swallow....