This is the difference between player thought and designer thought. The system might stick around, I'm willing to bet in some form, but I doubt we keep these exact weapons going forward. Who knows, but all this really is, is the paragon leveling system come to life they talked about in Cata (path of the Titans).
The system itself could easily show up again in another way. Even a true Paragon leveling system, where we find titan power and to unlock more we have to grind some kind of AP system, go to our little spot and put points in. We could end up with another piece of gear system. Or we could even end up with all new weapons. It wouldn't be hard to keep this system as it is just a leveling system outside the basic leveling structure.
I see the weapons going away so that they can rebalance or make class changes going forward. The Weapons either lock them in, or you have to re-level there are a various issues with carrying the weapons over into the next expansion that are easily solved by simply removing them and restarting us on a new paragon path.