KISS Easier and clearer to do just the one. Then one can add the other drugs as an update which is also easier to get approved. To the best of my knowledge.
I suspect it is because Ticagrelor (Brilinta) is an antiplatelet agent. Apixaban (Eliquis) and Rivaroxaban (Xarelto) are anticoagulants.
Don't forget that the company has had positive studies also where they demonstrated successful and safe removal of Dabigatran (Pradaxa) and Edoxaban (Savaysa) so I suspect those two agents will be next.