I predict the next Chief Architect will stall (or begin a rollback of) HHVM at Slack. Too much time wasted migrating onto a nigh-proprietary platform for a now ambiguous value proposition.
PHP has integrated a lot of HHVM typing features in PHP 7.x and 8 I believe, so that lessens the need
He also once wrote an article citing concurrency as a benefit of PHP and advocated services making web requests to themselves as a good way of achieving that. How that was taken seriously, I will never know.