We'll see a return to BC with many (lazy) people expecting gear from the second raid tier just to do heroics. Or more optimistically we'll see a lot of very over geared people filling up heroics and not really minding if they end up dragging along a few undergeared new players. My guess is that both will happen, depending on who you run into.
Runed orbs will plummet in price. 18 conquest feels a little high now when people are still learning Ulduar. Once those can come from only a handful of heroics we're going to see a lot more.
As a result of cheap orb, there will be very powerful (about the best you can get before hard modes) belts and boots which won't exactly be cheap, but I'd guess they'll end up around 1-2k. That's within reach for a much larger group of players than the current price of 6-8k.
PvP gear is going to inflate a bunch as people find themselves able to buy high-end gear. Previously their options were the easily obtained blue gear or the more expensive valor gear, which while the badges weren't hard to obtain, they couldn't be farmed so readily, limited to a couple dozen a week doing all available 25 man raids.
I won't call it a side effect since I'm pretty sure it's the goal, but the biggest effect will be much faster gearing of alts and new players. This will be a huge boon to guilds needing to recruit a few more people to either build up or to compensate for turnover.