Limited amount of Euphyllias out there already so I think you've seen the upper ends already on them. Montis are currently already raging with a handful of them pushing in the $500+ range already. Tenuis are in the same boat with 1" sticks costing upwards of $2k (RR jawdropper, JF homewreckers). The fad will continue with tenuis especially with the sheer number of wild rainbow colonies coming in. Mushrooms are still crazy as well with ecluctus, jawbreakers, etc.
The fad nowadays is actually just high end rainbows that will continue to dominate the scene for the foreseeable future.
Here's a new one that showed up recently with an undisclosed price. This one happens to be an anemone, a species of "pizza" anemone,
Cryptodendrum adhaesivum, to be exact.
It's currently not doing well and chances are that it won't make it, but I doubt that we'll see the last of these.