I replied to those GC tweets trying to highlight this exact issue. Not easy to get the point over in a freakin' tweet, but they really need to be forced to seriously consider this. I'm not convinced they fully understand the impact that this could have. I can see it going a few different ways.
A) s13 Honor gear has its ilvl buffed to match upgraded S12. Total gear reset. Ideal solution.
B) s13 Honor gear is remains as it is, fully upgraded players this season maintain heavy advantage until everyone has full S13. Developers justify this in one or more of the following ways:
i) 'Gear progression', we don't want to invalidate the gear S12 players have worked to obtain. They have been pushing the 'gear progression' line a lot so far this expansion in almost every aspect of the game. A threshold has been crossed in season 12 where gear progression is severely infringing on competitiveness, but it seems as if they are sitting back with PvE tinted glasses saying 'Yup, they are never done gearing! Now everyone can have fun all season long! We done good!'. This is exactly the wrong way to push PvP. Do sportsmen compete just to win the big cash prize from the world championships? Hell no. Playing, besting other players and improving your play is its own reward.
ii) 'The difference in item level between upgraded and non-upgraded is marginal.' Wrong. Competitive-minded individuals will leverage any advantage they can get, no matter how small, because in the top tiers of competition it is the tiny advantages that set apart the good from the best. A good example of this is the recent scandal surrounding Lance Armstrong. If you read the report published into his team's doping activities, you'll realise they went to some absoloutly insane lengths to obtain a fraction of a percent's increase in performance, because they felt that was the difference between 1st place and middle of the pack.C) They backpedal on removing the NPCs altogether, and allow upgrading of S13 Honor gear with Honor, but not conquest gear. Not my ideal solution, but acceptable.
Bottom line; Season 13 needs to begin with a gear reset to encourage better competition. I worry that Blizzard doesn't realise that competition is, in part, its own reward and will continue to push gear progression at the expense of a (somewhat) level playing field.
If option B makes it to live, I'm considering leaving WoW altogether. There will be very little left to keep me playing. Keeping a close eye on this in the days/weeks to come.