Apart from the rimfire lines, which I agreed have been supplemented well by Aguilla and Lapua, this looks like an opportune time for some of the smaller players (Black Hills, Browning, Hornady, SIG) to step up production and expand their rifle caliber market.
The danger I see is the extinction of factory ammo, and even brass, in some of the obsolescent/niche calibers. Remington doesn't list loaded ammo for some of its own proprietary calibers (6.5mm .350 and 8mm Rem Mag) - and brass for only the last two. How long before these are dropped (and maybe .280 Unimproved, .35 Remington and .222) to ramp up production of .223, 7.62x39 and the cartridge du jour (6.5 Somebody, .350 Epic or .19 Megadeath)?