Belinda, this is a great question! I touched a little on upcoming/continuing event design trends in this post on my company's blog; it's for 2017, but each section (colors, fonts, messaging) has a "what's next?" bit at the end that might work well for 2018. TL;DR would be:
Colors: a continuing glut (until they're overplayed) of rich colors like purple, scarlet, and deep green with metallic accents (bright copper or gold). When that runs out of steam, we might see an oncoming vibrant palette of vivid colors like cornflower, aquamarine, and magenta, contrasted by somber gradients.
Typography: hand-lettered type hasn't slowed down yet for display sizes or event collateral, but when it does crash, we expect to see basic, accessible fonts used well (like Open Sans for body copy, say). For headlines, we anticipate niche fonts used ironically, like blackletter or '70s style with clashing color/effects, and all-caps fading in favor of stuff that looks good in lower case.
Messaging: Effective restraint in all aspects of branding/messaging, for brevity, convenience, and maximum comprehension in minimal time. One hashtag at a time. Simpler/subtler logos & identity will leave plenty of space for interactive/crowd-streaming content that's more heads-up than heads-down (like Twitter walls).
These separate but related trends show attendees will expect interactivity, entertainment, and restorative downtime—a "festivalization of events”—not just a bigger or better bang for their buck.
I hope this helps you!