: If you don't propose they ever create new weapons, what if some or any of the
: new weapons became a tired brand/icon? What if the franchise needed some
: refreshing new weapons for any reason?

If I can give my answer to this: Halo is already getting long in the tooth. It's already getting restricted by itself, which is frustrating for fans and must be even more frustrating for people trying to produce content in it, and when it breaks those restrictions it often doesn't feel right (c.f. Halo 4). Having the weapon designs feel tired-- with the players, not the designers-- is probably a good sign it's time to give the series a break and either bring it back later, maybe with some new weapons or redesigns, or reboot it after some time has gone by and set up the new version differently if it's called for.