I have just searched in https://wikidevi.com/wiki/Broadcom and found that BCM43341 supported Bluetooth 4.0. And according to openwrt, they can run 6lowpan with USB4.0 dongle.
So I think the hardware is not the problem here.
According to Blogs - Nordic Developer Zone,
From kernel 3.17, Linux has supported 6LoWPAN for Bluetooth low energy (BLE) through the new kernel module bluetooth_6lowpan
So if Intel can release a new Yocto or Ubilinux with newer kernel version, we can add bluetooth_6lowpan to Intel Edison.
Actually, I can use Raspberry Pi3 (which is running BCM43438 supported BT 4.1) as a 6lowpan solution. However, Intel Edison is much smaller and pretty good appearance.
Sadly, Intel doesn't provide any officially github for kernel source code and update it continuously as the trending software nowadays.
Actually the kernel is being updated publicly in the following site https://github.com/01org/edison-linux. The information in this site is currently the only we have available.