Perhaps, one day. However, that doesn't change the fact that closed-backs have superior bass in quantity (+ quality with the TH900s) with great impact when in contrast with the majority of the open-backs. My part-time job is mastering and mixing mainly with electronic music. While I like to use my monitor speakers, sometimes headphones are a necessity. Sub-bass and the lower frequency region of <100 Hz is an extremely difficult task to analyze. From my inventory, the SA5000 is the worst in reproducing these frequencies and I was waiting for a headphone like the TH900 for a long time since it provides the quality that other closed-backs: DX1000, D7000/D5000, and Beats (these ace in quantity), lack.
Among my best headphones, the one weakest in quality in the bass is the closed-back CD3000. Even the ATH-7 electret -- generally reputed to be poor in bass -- is better.
Using the SA5000 as representative of what kind of bass open-backed headphones are capable of is anecdotally stacking the argument. D7000, like I recently mentioned, has a lot of strengths but bass is not among them. I think the problems with Beats tend to be 'way overstated here (it's the villain everybody loves to hate) but its bass is pretty muddy and bloated. Anything that got mixed to sound even on those is going to sound thin on well-balanced gear.
Several of Grado's headphones have excellent bass by any measure. So do the HE-6, HE-500, LCD-2, and some models of the HD800...
I've heard a couple different HD800s now, and I wonder if there had been mid-production changes in the model line. An early set I tried did not have strong bass at all (very articulate, but also very rolled off in the lowest octaves -- it was not subtle). Others I've tried since did not exhibit that roll off and seemed to retain most of the articulation.