WAB provides an answer to the question of scalabiity facing several blockchains. The TPS mark for WAB is expected to peak at 100 million compared with a maximum of 30 for Ethereum at present.
One other looming threat to blockchains is the introduction of ASIC mining that leads to high output within a short time. This makes it possible for a blockchain takeover to be possible for platforms that rely on mining. The threat of Quantum computing is also real as this provides an easy-hack into existing blockchains.