*You may have a maximum of +40.00% Critical Hit Chance from items.
*You may have a maximum of +250.00% Critical Hit Damage from items.
*You may have a maximum of +40.00% Attack Speed from items.
Those are caps from items. It doesn't count the amounts you get from Paragon Points you might spend, or amounts you can get from abilities and passives.
For example, there's a 40% CC cap from items, but you can get 10% more from Paragon Points, you have 5% by default, Scoundrel gives you 3%, Pinpoint can give you 5% more, 15% more from Deep Freeze, and the new Conflagration will give you 5% if you apply fire damage to the mobs (and there are a lot of new fire-related options coming in the xpac).
So with just the 40% CC cap from items + 5% default, 10% from Paragon, and 3% Scoundrel, you'll be fine. Hell, it's only 3% less than I have right now, and 2% more than you have right now. It will actually be a buff for 2H users since they don't get CC from an offhand but will be able to get up to 10% from Paragon Points to make up for it. How about that?
40% IAS from gear, 10% from Paragon Points. I'm at 1.89 APS with 1H SS right now, and I don't even have 40% IAS (I'm at 35% from gear). This won't affect me at all, and I run with more IAS than just about every other SS user I've seen on these forums so far. It could actually be a buff for me because I'd be able to drop some IAS from my gear, make up for it with Paragon Points, and then replace the lost IAS from gear with some new and better affixes that affect more of my damage sources (since IAS only helps SS and does nothing for EB or Storm Armor). And if you're a 2H SS user, the IAS cap won't even register on your radar (unless they wind up making some changes to AP consumption with channeled spells which in turn makes IAS more desirable.)
The CHD cap from gear is the only thing in question really. I'd lose 157% from my gear, but gain some of it back through Paragon Points (not sure what the cap is from Paragon Points, can someone clarify for me please?). But I still think it's going to be just fine. We have to remember that weapon DPS is going to skyrocket, and main stats like Intelligence are going to go way up on higher tiers of gear as well. That means that damage is going to be more smooth. Non-crits will be doing a lot more damage, but in exchange crit damage will go down a little bit, thus it'll balance in the end, and hell... more than likely actually go up when you factor everything in.
Capping these stats through gear also allows us the freedom to supplement our builds with some of the new Legendary affixes coming out that will lead to higher dps. It might not show up on the character sheet, but it'll still be dps. Or we can supplement with some of the new utility affixes like immunity to freeze and root, more ehp, more cooldown reduction, that thing that makes all Teleport runes act like Wormhole, etc.
This is a time to be VERY excited, not a time to worry. The game is going to be sooooooo much more interesting and a TON of new possibilities and options are going to open up for us. SS already operates incredibly well within these caps, so all the new stuff coming out is only going to make us stronger.