Inability to use WebSockets/long-polling is the primary reason I haven't been able to use FaaS as my API layer, so this is great news. I would say the primary barrier I see remaining is db connections for RDBMS. Where a normal persistent environment might just use connection pooling, and indefinite amount of lambda instances connecting to a DB requires a separate instance running something akin to PGBouncer. It's possible that this is simply the long term solution, but prior to this announcement I would have said that bi-direcdtional communication with a client on FaaS architecture was not going to be possible, so I'd be interested to see if an alternative service or bit of functionality crops up.
