I think that every single rack might be filled with gen1 at the moment and here is why.
I found that each row has 92 blades and each rack has 3 rows with 20 racks. Assuming the blades are getting around 13gh/s per you would get:
13 x 92 x 3 x 20 = 71,760 which is pretty close to what FC said AM was hashing at (I think he said previously 67th/s).
Hmmm, we have 92blades on one "big blade", here >

how many of these big blades fits in one "bath container", if you think that only one, then you're right, but i see space for maybe 6?

When we're considering that each rack has 3 of these containers, you'll get : 13x92x6x3x20 = 430560(overclocked)/331200(normal) or 331Th ... exactly what you need for 10% of the network, like we had for few hours yesterday

Unless you plan in immersing the PSUs, you'd need a redesign too.