This is my first prediction I made which is on the possible characters coming the rest of this year (2019) and next year (2020). Well, I could be wrong, but here we go:
Toy Story 4 (Most likely Bo Peep, Ducky, and Bunny) are coming this Friday because the release of the movie
Inside Out (Joy, Sadness, Anger, Fear, Disgust, Bing Bong; not all characters will come) will come because it was announced by @Polaris either coming June or July
Kim Possible will come because she was supposed to come with Goofy for the anniversary update but not finished yet. So she might come in July or August
Unlikely Lion King characters might come even though their live action movie comes in July
Anna might come for Frozen II
Ariel might come for her 30th anniversary
Unlikely Jasmine and Jafar might come since their live action movie was a few weeks ago, but they might still join
Mulan characters might come in 2020 because her live action movie is coming that year
Emoji Blitz will release Sword in the Stone characters so maybe more of these characters might come to DHBM(Most likely Arthur and Madame Min)
More Beauty and the Beast characters might come according to Disney Wiki (Most likely Belle, Beast, and Lumiere)
And more to come…
So that is my prediction. I could be either right or wrong, who knows. Tell me in the comments on possible Disney characters that will be coming soon with proof.