COme on man, you know a PLX8606 bridge is used, how else would anyone do it? You need one lane for any NIC or even Intel PHY, Audio Codec like ALC898 doesn't need a lane, but a creative IC like CA202K or CA0132 needs a lane. Then USB 3.0 controllers use a lane, an extra marvell controller uses a lane. I think they perhaps feed the PLX8606 which is a 6 port PCI-E IC which can take 1 input and give 4 or 5 output ports, or take in 2 and gie out 4 which is what GB is using. That would give them two more device connections like for PCI-E 1x slots or extra SATA or USB3. But also In any case you only need 4 PCI-E links, GB doesn't take them from the CPU, that would be suicide(who would buy a Z77 board with less than 16X lanes for the CPU?) and not needed.You're not correct.
Thunderbolt lanes are like this:
10Gb is for DATA
10Gb is for Video, 2560x1600 requires 7Gbps
so... only 10Gb for data (which is twice that of USB 3.0)
What I'm more interested in is where they're getting their bandwidth from. they either need to tap off PCI Express lanes from the CPU (reducing graphics performance (NO SLI!) or utilize PCI Express lanes from the PCH which are, honestly, already in short supply on Z77 (DMI 2.0 is 4x PCI Express 2.0 or 20GB/s)
At the demo at computex they used those RAID controllers with a lot of drives, i think those devices are very expensive. I am unsure how well thunderbolt will do, i am sure some MAC users will like them.