I just used the new system to add someone to my tree (unfortunately if their user name doesn't match them when they are already in the tree, it doesn't necessarily match them - as I discovered, but recognised it when I added that person manually) - but it added the new person with a tag "DNA Match" and an immediate blue DNA match logo - which seems useful enough. It is to be noted that it simply added their name as in their profile, matched them to the parents as per Thru-lines, but added no further information, so it is not taking any personal information from the other person's profile or account.
With the individual who was already in my tree but whose username didn't match, it offered me an empty "add individual" as it was unable to give a name for the individual.
Edit: It also adds a Source to their fact page, noting that they are sourced from an individual's DNA matches.