Evolve 84 IV Dratini?

84% is good enough for me especially now CP is not that relevant in gyms.

Of course, you can wait for dragonite raids which should come in less than a year.

I would say yes also. I was in the same boat as you up until last week and mine was a 91. A little better but not amazing. I went for it.

mine was dratini 87%, evolved with moveset dt/hurricane, go for it..

overall I would say yes, don't hesitate. 84 is still a solid IV. No reason to deny yourself a Dragonite any longer.

But what you didn't say was what level he is. If he's 84 and also low level, I might not.

What IV would you be holding out for? I assume you are aware that an 84% IV Dragonite will have a CP that is about 2% lower than a 100% IV Dragonite at the same level. That is not a difference you would notice in practical use.