FPGA's boost in hashrate is relatively low than what ASIC's are capable of. With new GPU's coming out this september, we would see another hashrate jump again.
Depends on how they hash.
They are priced too high for gamers, and hash too slow ( estimated ) for miners.
That would be like saying the Nvidia Titan V was going to be a threat to other miners.
Yes it hashes faster but price/performance ratio is way too high.
The 2080 Ti will have the same problem.
The only place it could be competitive is with Ethereum due to the GDDR6 Memory, but even then used 1080 Ti still beats it.
We will have to wait til AMD comes out with their Next Gen GPUs before anything will change in mining.