This has been discussed on the couple threads dealing with the new FM2+ Mobo's but if you missed it, New Egg has a good selection of them now including Asus, Gigabyte and ASRock which all lines carry 1 or more PCIE-16 3.0 Slots with use of the New Richland CPU's, but have a look for yourself here:
http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=100007625%20600469846&IsNodeId=1&name=FM.... As to the Crosshair Series Give it up till the new socket lands next year....the AM4 which will not only support PCI-E x16 3.0 but also a whole lottof other things like DDR5 Support better USB3 and SATA 4(Rumor at this point) but also remember that with this socket comes the SIGNAL of the End of the CPU! AMD has publicly stated a long time ago that they are going ALL APU and Intel has also stated this with the Haswel also.
Here are two of the MoBo's I'm looking at-
http://www.newegg.com/Product/Product.aspx?Item=N82E16813132050and-
http://www.newegg.com/Product/Product.aspx?Item=N82E16813128655Although I'm looking at the Gigabyte more due to the fact that they are the only ones that have Dual PCI-E 3.0 that can run at 16x0, 8x8 or 8x8x4 not only 16x0, 16x4. Plus they have more Features than the Asus line like Dual Bios, USB Noise Filters, USB Over Current Protection...on and on which all of this Asus could give to their AMD Customers if they weren't so worried about only Their Bottom Line, because Gigabyte did it affordable.