We've been hearing that this will be a solid year for third parties for a while. But it is likely to be a port heavy line up again.
I'll definitely be surprised if Nintendo can best their 2017 output somehow (not in quality, but at least comparably sized new exclusive experiences).
The first half of the year had Zelda and Arms vs Mario Tennis and Kirby. That's a lot of ground to make up already. Then the 2nd half had Splatoon 2, Fire Emblem Warriors, Odyssey, and Xenoblade 2.
What seems likely for the rest of the year (Smash, Yoshi, Pokemon, Fire Emblem) would make 2018 solid but probably not equal to 2017 imo. Retro's project could definitely change that outlook though.