The most popular FPS of 2037 will be a fingerguns RPG hybrid where characters’ adherence to the kayfabe of imaginary Uzis, grenades, pump-action shotguns and headshots depends on your relationship with them. We can’t predict the direction the genre will go on, which weird addition or experiment will catch on then be repeated and iterated upon for years, compounding with other oddities to make something bizarre.
For now, in 2015, perhaps the answer is a pogo stick. That’s what Pongo [official site] went for. It’s out now, so you can judge for yourself whether it’s a vision of things to come.