According to Automattic they had been in discussions for 20 months. Your anger should be with WPEngine for taking your money while knowing full well their service depended on servers ran by a company they were on (best case) shaky terms with.
Up until about 8 months ago, Bluehost (another big paid hoster of WordPress sites) ran its own plugin mirror with no issues: https://github.com/bluehost/pluginmirror