If you've got a Jewelcrafter that you've been neglecting recently as part of your gold making lineup, you'll probably want to ramp things back up for a while. 5.4.8 which was just released on EU/US servers adds the ability to upgrade pieces 4 times as opposed to 2.
At face value it may not mean a lot, but people will soon be upgrading pieces with hit or other stats, and their gems they used to gain hit/expertise/haste/whatever caps will now be superfluous and they'll need to optimize their stats. Unfortunately for Enchanters, a lot of Enchants are best in slot for a certain spec once they hit a certain ilvl, and when they can switch around gems rather than drop those enchants, they'll usually do so. On top of that, the gear bonus is basically a nerf to SoO, and people will be running more SoO's and downing more bosses. People will definitely buy more enchants, but in my opinion the change in sales in Enchanting won't be comparable to the changes that Jewelcrafters should see. All item enhancements should at least see a few extra sales, but I think the bulk will be in JC.
Since the Garrosh weapons auto upgrade, the minimum Valor a player (with Garrosh weapon(s)) will need is 7,000 Valor to upgrade the rest of their slots from 2/4 to 4/4. If they were Valor capped heading into the patch, they'll be able to get the 7,000 in the next 4 weeks. On the other hand for those not Valor capped or not even upgraded to 2/4 yet, it could take anywhere from 1-4 months to get all the Valor they'd need to upgrade their pieces. What this should mean is that for the forseeable future, the gem and enhancement markets should remain stable, and for the next month or so, where a bulk of the upgrading will occur, they should do better than they have the previous month.
How Should I Compensate?
How you should approach this really depends on your server, so go with your gut. I play on a small server, and I've increased the # of gems I post at a time by 1, and considering upping it a bit more when I post for the overnight/Tuesdays/weekends. You may be better off posting more often, or increasing how many you post at a time by a larger number, or just stick to what you do, confident that you'll get more net sales regardless! Just keep in mind gems should be very much worth posting for the next 2 months or so, so keep it as part of your routine!