They fall in a middle ground between things I can build more simply with a super cheap microcontroller (I buy Arduino nanos for $2, for example), and things I really need GPU compute for. So I'm stuck. I keep thinking I'll do a DSP project soon, but that's more because it is one of the few things I think an FPGA will be useful for, than because I need it.
So cool, yes. Practical, maybe - but not very, at least for me.
Things like the ZINC by Xilinx are working its way into things like the Red Pitaya[1] which is absolutely remarkably capable for the price range, but yeah FPGA's are pretty niche for the common end-user. Lithography on sil wafers ends up being cheaper at nearly any scale. It turns out more economical just to do that one of those cheap FPGA-to-ASIC conversion dealies (rather than using Cadence or whatever VLSI tooling you have to DFM from the start [I think UC Berkeley has a full architecture/RTL/logic/circuit/physical kit]) at the threshold of around a few thousand units.
I think this point is overstated. FPGAs are not microprocessors. I don't think an OSS toolchain would be anywhere near as beneficial as something like gcc. It would be nice to have but it's hard to think of any problems specific to programmable logic that this would address.
What would help is toolsets with less friction and less of an entry barrier.
I love FPGAs. They're awesome for interacting at a low level with just about any kind of hardware, at nano-second-level latency.
But although I bought one, I don't think most people will end up buying one, unfortunately; the vast majority of the consumer stuff that we considered putting on FPGAs in the past (graphics rendering, heavy math) is solved six ways to Sunday by today's GPU. The FPGA also lacks an open-source (or even shared-source) toolchain, there's no way to perform resource sharing, they have code constraints that are physical limits, and so on.
Basically, FPGAs rock when used for chip design or for powering custom prototype or small batch hardware. But they fall into a really narrow portion of the market, because there are few cost-effective consumer-level solutions that make use of FPGAs.
A shame, really. They're super cool.