As with everything else, standards and product manufacture will be dictated by the market need. Cat 6e and Cat 7 has to be approved first by TIA/EIA too -- right now, those are just unofficial marketing terms conjured up by cable companies and if you purchase one, it is a non standards based cable which is used at your own risk. As of date, there isn't any plan(s) to establish Cat 6e or Cat 7. There is however, a Cat 6a that has the capability to run up to 10Gbps and defined by TIA/EIA 568-B.2.10.

You are right to say that noise plays a big factor in lowering the data throughput but the industry now seems to have moved towards educating the installer with best practices (of installing it correctly in accordance to your environment). Such is proof with the recent TIA/EIA 568c standards that was released too. Common best practices in industrial environments with a lot of noise is proper routing, grounding and shielding to name a few.

I would also go as far as to say that a good cable is not just what the Category name states, rather more importantly is how balanced it is when manufactured. Rather than go through a lengthy explanation of what the definition of balanced is, the short version of it is... it is a the way the pairs are twisted together (and how uniformly throughout) so that it has almost identical impedances and reduces interference from electromagnetic induction (by cancelling it out). So a more balanced cable may be less susceptible to noise than one that is less balanced -- even though they a stamped with the same Category label. In summary, the Category label states what kind of cable and standards it references but the threshold level to how the manufacturers makes/tests the cable may be at a minimum (borderline) level rather than at the high end of the standard numerical reference.

Reputable cable companies have very balanced cables which may be one reason why you pay more for it -- they do not just manufacture a cable to minimum standard references. A colleague in my previous company was one of the leaders in this field, heavily involved in testing this and working with several of the bigger cable companies, and I know first hand which ones were recommended. If you need to know who the those recommended companies are, I can let you know in private.

Gigabit/ 10G/40G ethernet in industry is a long time away as there isn't any control system, PLC, instrumentation or drive that supports it right now. There is no doubt that the time will come but we're just not there yet -- there just isn't the pressing need for gig ethernet right now. There seems to be a bigger focus to improve the real time/ deterministic nature of ethernet in industry too. I heard a number of years ago that there was talk of a Category 5i which was a specific industrial based cable supported by many of the major cable manufacturers but I don't think it ever came off the drawing board.