Is there any route to possible to have access to the resources in large bitcoin mining warehouses as they approach the point where the cost > value of the bitcoins mined?

eBay
Equipment gets sold on eBay and other classifieds to get rid of old equipment or unused.

The other thing is ASIC miners. BOINC is supported by this equipment but I'm unsure about the projects.

Then again there is nothing stopping you from reaching out to these Bitcoin warehouses making a request or paying for time processing BOINC. It's no different from Cloud providers

Is there any route to possible to have access to the resources in large bitcoin mining warehouses as they approach the point where the cost > value of the bitcoins mined?

If they are gpu's then yes most Boinc Projects, that have gpu apps, and Folding can use gpu miners. I'm not aware of anything except mining itself that can use Asic miners though.