Currently today we have an option to use a dropdown control which allows for multiple select items.
This is not what dropdowns are intended to be used for. It is checked listboxes that are used to allow for a easily viewable multiple select control.
I am referring to sharepoint list choices. Basically when you are adding datacards to a form or canvas you should be able to have a Checkbox list - today we only have View/Edit Multiselect which gives you a dropdown box.