Midway actually has percussion caps (in one size), .50 BMG primers, and EtronX primers. And there's where I burst into spontaneous and uncontrollable fits of laughter.
Now if ever there was a wall banger of a rifle idea, the Remington EtronX would qualify. In principle, the concept of an electronic trigger makes a modicum of sense, in applications where the presence of batteries (dead batteries, most noticeably) in one's bangstick was not life- (or trophy- ) threatening. If all that is needed to let off an electromagnetic sear is a closed circuit, the trigger can be tuned to an absurd degree without affecting function. Walther (unsuccessfully) and Morini (quite successfully) rolled an e-trigger into free pistols, and the majority of competitive paintball guns are equipped with them.
The reason the e-trigger works there is that it's just the trigger that's being messed with. The EtronX used proprietary primers in special runs of ammo for full-electronic ignition. So essentially you're trading a tiny decrease in lock time and a potentially nice trigger for a gun that relies on batteries and obscure-ass ammunition. Predictably, that went over about as well as a lead balloon. Worse, really, since one could melt down a lead balloon and cast bullets from it.