I know they usually keep around old gear but with all the changes going on I can see them getting rid of most of the old gear. I wouldn't be surprised to see all but the last tier of PvE and PvP go bye bye.

If the PTR is correct, then yes, all current gear will be purchasable with justice points. I ran a heroic on my lock and recieved triumph emblems which were immediately converted to justice points, meaning you can essentially grind heroics after 4.0.1 launches and purchase t10

I find it a little frustrating that Emblems of Frost and Triumph are being treated the same. It's not to say that my ICC 10 progression won't be over before 4.0.1 drops (though from the 2.5 hours spent last night banging our heads into the LK, I wonder), but it definitely creates an incentive to stop raiding ICC if I don't really need any pieces from there and just spam heroics again.

Boo-urns.

Yes- that definitely appears to be the case. The numbers on the PTR (at least as of yesterday) seemed a little borked with various items costing several hundreds of points to acquire. It will be interesting to see whether the new price will simply be current cost * 2.75 or if the multiplier on the cost side would be larger. I could see a valid argument for either side.

Now that we know the conversion rate, does anyone know the kinds of JP costs the T10 pieces are? Did they just do 95*2.75 for a T10 chest for instrance and 23*2.75 for a primordial saronite?

What's one more time?

Currently, stuff costing Frost on live is going to take a little less than twelve times that to buy with Justice on the PTR, i.e. t10 gloves/shoulders go from 60 Frost to just under 700 Justice.