Actually there is a good amount of evidence for it and it'd give a point to ~Daario~
similar physical appearance
both have blue eyes
Euron's location was unknown during Dany's conquests and left Westeros shortly after Victarion
Daario wasn't in Meereen during Balon's assassination and Kingsmoot
Euron brought a huge amount of swag to Kingsmoot
Daario earned a huge amount of swag after the siege of Meereen
Euron's sure that Dany will marry him and he'll get the dragons
Daario tried to convince Dany to organize Meereen's own Red Wedding, which is a weird coincidence
The Warlock prophecy mentioned "three mounts you must ride, one to bed, one to dread and one to love." Dany has had sex with three men, Drogo, Hizdahr and Daario. Drogo is the one to love, Hizdahr is the one to bed so by elimination, Daario is the one to dread.
Dany saw 'grey lips' when "dread" was mentioned. Euron has grey lips and is a GREYjoy.
Euron's the biggest threat Dany's facing (acc. to Moquorro)
Daario is a pretty pointless character with an unknown motivations
There were always month+ gaps between Euron's and Daario's sightings, almost two months long before Balon's assassination.
It's implied that Euron's using quarthian warlock magick while sailing, so anything makes sense chronologically.
Horn's ownership must be paid in blood - Euron killed a king once.
Euron's introduced as a cunning chessmaster and seems to be playing Victarion in some way, yet he didn't do anything yet, and isn't even in Meereen.
And:
after Daario's actor being specified as "any race except caucasian" in the casting material, HBO made him white after all.
GRRM said in a post-ADWD interview that there is more to Daario than there appears to be
And finally:
Daario leads a mercenary group called the Stormcrows
Euron is known as "Crow's eye"
Euron describing himself: "I am the storm, my lord. The first storm, and the last"