ZDC Center Controller reported insufficient training for new procedural routings could cause a controller to overlook a potential confliction.

Narrative

I've found another reason why this new Florida Metroplex route change from last week is a safety issue. Here is another way that our traffic has changed that could create someone having a deal (separation loss). I received 2 aircraft from sector 50. They were at separate altitudes so I did not have a deal with these two planes. However; if they would have been at the same altitude or one would have asked to climb to the others altitude; I don't know if I would have caught the problem. The front aircraft was Aircraft X going to MIA; he was still over DIW because we can no longer short cut the MIA's because of the routing change. The back aircraft was Aircraft Y going to FLL and was already short cut to OSTNN because W122 was cold and that is how most of us work. When I got these two planes they looked separated laterally (again; yes they were at different altitudes; but I look at all planes as potential conflicts in case I need to move one or they ask for something different). I realized that if they were at the same altitude they would 'look' separated when I took them from (sector) 50; before DIW; they would come back together. This is a major change on how we work this sector. FLL and MIA used to always stay separated. And most of us always shortcut these routes when W122 is cold. I fear someone will have an error or worse when they are not busy and they do not have time to assess and relearn these new routes on live traffic.We need to go back to the old route structure until real training can be accomplished on this change. We need simulator training on all the new confliction points. This is not safe! Someone is going to have an error from this!