When you consider the scarcity of many popular loadings due to ammo shortages (military contracts, lack of raw materials, etc.), I believe the WSSM's will become obsolete with factories ceasing production runs within 5 yrs. Why would Winchester, Federal, etc. use valuable production time & material doing runs on WSSM ammo that sits on the shelves? They need their loads to sell at both an attractive margin and volume. Their margins may be good with WSSM's but I seriously doubt the volume sold justifies the manufacturing time.
With regard to the WSM's I believe the 270WSM, 300WSM and 7mmWSM are here to stay. We'll continue to see rifles produced in these calibers by several manufacturers. Shooters will continue to buy them because the ammo manufacturers are producing excellent ammo in a variety of loadings. Reloaders will continue to shoot these calibers because they do perform as advertised. Also, bench and tactical shooters will support the 300WSM and 7mmWSM because these rounds have 1,000yd capability, the cases are not belted, the rounds are short action and cheaper to shoot than the .338 Lapua. These two calibers are also legit calibers for pretty much any North American game animal (short of brown bear), giving versitility to the hunter who wants one short action rifle that can do it all.
Not saying that we didn't already have these capabilities before the WSSM and WSM calibers were born (30/06, 300 Mag, etc.) but these 3 WSMs compliment the niche nicely.