I believe it was an intentional decision on the part of the creators not to show the constitution refit in the series. The Constellation, after all, was supposed to be a constitution. From what I've read, the Bozeman also was supposed to be a constitution, but to save money (And the mysterious other reason), they refitted the Miranda model into the Soyuz class. I believe the only reason the excelsior, Miranda, and Oberth stayed around was because they could not afford the cost to feild new ship designs. (Though feel free to enlighten me if there is a real reason why the Constitution never appeared).
I believe it was contempt for the design, personally, since the TNG staff wanted to trump their baby and ignore the past, but that's my own opinion.
Back to this design, I like how it harks back to the original BoP, in whatever time period it's set (TMP?). It obviously looks like the "new series" Romulan battleship from SFB, which makes it a nice candidate for a cost-saving measure to just update some of the old designs. Could be a stablemate to the TOS warbird -> KA warbird, which seems to be an obvious refit of an older design.
In the end, maybe they became monitors by the TMP era? That's what happened to the Union Navy's old ironclads at any rate, which were considered the first battleships at the time of the civil war.
Anyways... Atlom, is there an ETA on this design? Or is it one of several floating. If it's released, she'll fill my sublight Romulan BB slot, since IIRC it is filled by a regular BoP in the stock game...