I like to think that, over years and years of living with ponies, especially Fluttershy, Discord felt less and less inclined to be chaotic. It’s not like in Discordant Harmony, where he was trying to force himself to be normal. He just slowly, naturally, learned how to get along with ponies and grew inclined to be that way when he saw how easily it allowed him to make friends, plus he still used his all powerful magic to get things done.
 
Anyway, I imagine him eventually spending most of his time in the form of a pony and looking like this.

I wish there was at least one vector of Discord in this form

So, Discord has white magic aura. Called it!

I didn’t notice when I was watching it that his horn was still blue. Nice touch.

So after all this time we find out Discord’s cutie mark is a twister which is fitting

@Inkan1969  
for breeding purposes

John de Lancie voiced Mister Twister in Young Justice.

It’s a walking tornado of chaos.
 
Actually quite fitting.

@Background Pony #649A
 
Why does he need a pony shape to date Fluttershy?

Well in that shape he could date Fluttershy  
(Discord pony ass is canon)

Tornado’s a good cutie mark for a wild guy like him.

So.
 
His Cutiemark is a tornado.
 
Huh.