:P

It's an interesting question I will give you that, but it's also hard to pin down or quantify from a technical standpoint. Given that pixel art is itself an adherence to a technical restraint of a previous era which imposed a particular artistic influence, it's hard to imagine taking it beyond the shackles of said era.

It's also subjective somewhat. What do you define as "next evolution"? More sprites in the animation? Smaller pixels? You know what's got really small pixels? Present day games! I think Evoland would qualify as next-evolution of pixel-games certainly, it its representation of several different constraint-types and the particular styles that went along with them.

Beyond that it's hard to say. Fez? In that it combined 3D with 2D. I think next evolution has more to do with elements of the game outside the actual pixel-art itself as there really isn't anywhere to go with the actual retro itself if you're doing retro to begin with.

How about a game that combines 2D and 3D at once? Characters and environments that are partially pixel 2D and 3D simultaneously.

http://i.kinja-img.com/gawker-media/image/upload/s--hyxV4PJr--/c_fit,fl_progressive,q_80,w_636/do18u7g2jebs9tmbzzxm.jpg

Something like that. A landscape which is painted or pixelly but structures and people which seem higher-fidelity and stand out. This could lend itself to a sardonic darker fantasy setting where the dissonance of the world's inhabitants created by a higher fidelity and apparent lack-of-connection with their environment imposes a sort-of arrogance and antagonism to those inhabitants while simultaneously allowing for a perkiness and positivity to the environment resulting in an interesting dichotomy that allows for a bleakness that becomes stylistically approachable for classical high-fantasy styles.

(•_•) / ( •_•)>⌐■-■ / (⌐■_■),

YEEEEEEEEEEEEAAAAAAAAAAAAAAAAAAAAAAAAA

How about a game where people transform from one pixel form to a higher-grade pixel form. Again this is just like Evoland but I was thinking like transformers and megazords. Like it's all done fluidly so you can see it happen in the transition.

edit: A game where you eat pixels! You eat everybody! And when you do, you get more pixels! There's a pixel counter in the bottom of the screen and you can spend pixels on becoming a higher-grade pixel character which can do better things. Little block pea shooter? Become fireball launching arm of doom! BOSS BATTLES! Boss battles where you eat bits of the boss and as you beat them they recombine to become simpler versions of their previous selves to make better use of their lesser amounts of pixels! The whole thing can be set in a 3D world and what happened was the pixel people came in through a portal when the Black Mesa facility turned on the doo-hicky and they took over!

Isn't that what is happening already?

Pixel games are smoother, and more complex than ever. Just because not everyone use them like this, does not mean this has not already happened. There are limitations, but there is a constant growth within the constraints. I am still not sure what you are after....