Not really. Nothing stops Sony from using SSM to develop a sequel to The Order: 1886 since they own the IP. But i guess RaD will be the one who will develop the sequel as well. Of course, this is all after the game actually manages to sell well and establish itself as a successful IP.The IP (The Order: 1886) belongs to Sony.
The Order: 1886 is going to be a trilogy, according to RAD.
So yes, they have "restricted themselves" to one platform this gen.