At the end of the day, the chip is a physical thing that have to be produced by someone. As long as there is no 3D printer, which can build nano structures to makes chips, I can only implement it into a FPGA. The main FPGA providers are either Altera or Xilinx and both a very expansive. So they are good for prototyping or very low volume. But for anything beyond, I need a specific implementation. Okay, I could go to a foundry like Samsung (or other) and order according to my design. But, even that requires a very high volume in the millions to make it affordable and viable from a business perspective. Especially, if it is intended for the IoT market. On the other side, I can buy ARM Cortex M0 and Cortex M1 for cheap from NXP and other for less than $1. They are power full and power consumption is very low.
Just to mention, the other day the WRTnode[1] was released for less den $25 or look at an Raspberry PI Compute. Don't get me wrong, Yes, I would like to see those with an open source chip. But would that be really a viable business case, except from the University context?