You have a bunch of things to do before you hit any kind of wall. When you get to 2.73 with 5k armor and 700+ Resists you'll start to hit a wall. You're not there yet.
1) I've read about a dark mage shade. I've found a dark mage shade. I've never seen anyone use a dark mage shade. This is not a place to be a trendsetter though! You need 18-20 APOC and 800 LoH. You get both APOC and LoH from SC. I'd get one with 400+ LoH, up towards 400 armor, and 70 All res. You can trade out for one with CC once you have enough all res elsewhere.
2) You have a pretty good Nats Ring. Y U no Nat's boots?!? Get a cheap pair with 80 INT for like 1M. Later, you add a double dex roll (for about 10M) or vitality (15M+). That'll boost your CC by 7. That's huge
3) You're Chant Will is really nice. Moderate DPS but high AS. That allows you to skimp on IAS elsewhere. Even though you have 9IAS on all your pieces, you can't drop one of those pieces and make the 2.73 breakpoint unless you get a 1.78 wand. Then you could drop IAS from a ring, ammy, or glove. Since you already have 9 IAS on all your items, I'd be tempted to spend some time looking for a 1.78 or 1.79 (like mine). You'd have to drop, like, 50-60M to get one with my DPS (which isn't alot) because they are at a premium. The interesting thing with a 1.78/1.79 wand is that if you add two more 9 IAS pieces then you'll be at the 3.00 breakpoint. Something to think about. If you stick with your current wand, then you can feel free to drop some IAS from an item and still hit the breakpoint (i.e. get a 6 IAS Ammy with 9 CC and whatever else you want. It'll be alot cheaper than the corresponding 9 IAS one. Save gold there).
4) You need to be adding major armor (or STR) and all res everywhere. Where you are, its better to add some all res and armor everywhere. That's affordable. getting max armor and all res on most pieces is not. You can get one good piece for 100M or 3 to 4 decent pieces for 100M. For instance:
Blackthorne's Jousting Mail: 650 armor and 35 all res....under 20M
Tal Rash's Relentless Pursuit: 600 Armor and 30 all res....probalby 20-30M
bracers: 65 all res, 450 armor, 60 int, 70 vit, 5 CC....less than 5M
Vile Ward: 100+ STR, 75 VIT, 180 INT, 625 armor, 75 All res....probalby around 15-20M.
(you can certainly get better items than these suggestions if you can afford it)
Just check out my toon. My gear is pretty good...but not anywhere near endgame. Most things like I said were under 40M.....which is what you should be shooting for...10-25M upgrades. Spread the money around!