I don't know that 37Signals counts as a "major enterprise". Their Cloud exodus can't have been more than a few dozen servers, right? Meanwhile AWS is growing at 20%/year, Azure at 33% and GCP at 35%. That doesn't seem compatible with any kind of major cloud repatriation trend.
"At the moment we have somewhere between 20-25 servers in each cab, or about 90 servers in each site. Here’s what the rack layout looks like in Chicago, for instance."
- https://dev.37signals.com/37signals-datacenter-overview/
Their "server count" is definitely much higher than what you are thinking.