Fire, like other crit-based specs (Balance, Fury), has always been fairly gear-dependant. Even with reforging, it took a decent amount of gear for the spec to come into its own. I suppose the concern that, with reforging gone, the time it will take to reach that point could be longer is a valid one, but it's really too early to say. Hopefully, with Blizzard's new focus on making all secondaries at least somewhat valuable and the addition of things like Enhanced Pyrotechnics, there won't be as much of a gear discrepancy as we're used to.
Also remember that all enchants are secondary stats only now, and gems (which I think are also only secondaries) will give much more of a benefit than they do currently. Even if you only have 2 or 3 slots on all your gear, that's potentially a lot of crit (or mastery, or multistrike, or whatever you might want).