Depends on their need; I tended to move them to managed hosting, which used to reduce their hosting costs massively and reduce their devops costs. Hetzner for anyone with most traffic in Europe. DigitalOcean in some cases. Sometimes we just put caching proxies (external to AWS) in front of EC2.

I've managed racks for customers too, but managed hosting at Hetzner is now usually cost-effective vs. colo-hosting in London where I am. Since they also offer cloud services (though pretty basic) now, there's the option of mixing and matching.