In short: Hell no for another year at least.
The highest event eidolons will go is 50% element, and most* of those require all of your sub eidolons being of the same element.

*Up until last week, I would've said all. But the latest event eidolon, Fleurety, works with a new type of bonus, 'special attack', which SSR Diabolos also has. The fact that 'special attack' is its own multiplier instead of adding onto character or element is actually rather potent. But the catch with Fleurety is that the actual amount of special attack goes up to a max of 50% depending on how low your HP is. Think of it like a version of Pride that goes in a separate category instead of stacking on assault/character.