DHS really doesn't need another thrill rides than the Total DHS will be running in 2020-2021. DHS is a getting 1 or 2 more thrill rides in Star Wars Land. DHS already had 3 thrill rides. The other thing Toy Story Land already is going to get a coaster with it being a kids coaster. Disney's unannounced Phase 3 is unknown if it will have a thrill ride. Right now based what we know, DHS in 2021 amount of thrill rides will increase from 3 to 5-6.
The crowds at Toy Story Midway Mania isn't caused by not having enough thrill rides, but not having rides that aren't considered thrill rides of any form. The amount of people eater rides DHS has also isn't helping this at all.
I am mentioning this because that is a problem with DHS right now and the 2nd thing is DHS in the 2021 time frame isn't going to have the amount of shows it does now along with no One Man's Dream. Not having LMA and Indiana Jones Spectacular is going affect the amount of non thrill ride stuff for Guests along with the possibility of Voyage of the Mermaid being gone.