Remington's electrically fired ammo came and went quickly over two decades ago. The Voere case-less electrically fired ammunition was also a failure, almost a quarter century ago.
Remember the Gyrojet of fifty years ago? Those spin-stabilized rocket projectiles started out slow, built up velocity, and then petered out.
And before that there was the ungainly Dardick, which fired Trounds.
I'm old enough to remember all the hoopla that accompanied those things. I actually thought the Remington and Voere designs had promise, not that the traditionalist in me liked either one very much.
But not the Gyrojet. I thought that one, which showed up about the same time as turbine cars, came about only because of the rocket and missile craze. As for the Dardick--beauty is in the eye of the beholder.
What has been successful? Well, for starters, non-corrsive centerfire self contained metallic cartridges with smokeless propellants and advanced projectile designs!
More seriously, when I was a kid they didn't have good-looking, stable, and strong composite rifle stocks; great recoil management devices in shotguns; rangefinder scopes; laser sights in pocket guns; or very reliable affordable polymer pistols.
I think that further advances will probably be seen in materials and manufacturing methods.
BTW, I've limited my thoughts to small arms.