At the risk of oversimplifying things from a distance, this site -- especially the free, public-facing part of it -- seems like it would be an ideal candidate for a rewrite using static site generator/framework. That, coupled with a bot-aware CDN should keep them online at a reasonable cost for many years to come.
Otherwise, I'm very curious to know more about their old and new architecture and what sorts of mitigation/scaling strategies they've started using to keep the site online.
Otherwise, I'm very curious to know more about their old and new architecture and what sorts of mitigation/scaling strategies they've started using to keep the site online.