CC would know better than us if this would sell at a run of 400. They'd have to just go over their data for the 1st and 2nd SA20/15.6 runs and see how many of each sold in how long. Likely require info gathering from stores that sold them but I can't imagine it'd be a far stretch for them to ask. Hell, go find the SA20s and 15.6s left in stock everywhere and subtract it from the total runs (on the second run this is easy as the make number is listed on the side). Edit: for those about to fear monger on the info gathering of rifles sold, I'm NOT suggesting providing personal information of buyers. I'm simply suggesting numbers of rifles sold over X months.
Other case scenario, they gather the data on the kits than have been broken up and sold as uppers, lowers, gutted lowers, uppers sans handguard etc and decide what style of production they want to run. Just lowers with the accessory kit to adapt a 5.56 upper?
Asking the community is one thing, and if they go that route, they need to make the request more widely known than second hand in an obscure post about this rifle. But going over passed civie rifle sales data will give them a more accurate representation as to the viability of making more for us. I think 400 at the right price will sell (but when has the "right price" ever been associated with new CC gear, lets be honest). Mind you, if the dealer and retailers produce a healthy IOP price, expect that market to jump on board as well.