Whats happening to Estimation?

There used to be a time when every customer wanted the vendor to give detailed estimates for testing their application. I have seen estimates planned for 2-3 years from the engagement start date and that'll include resource ramp up/down plans, cost planning based on resource plans etc. All this seems to be changing now.

Some of the recent customers we have signed up are not interested in Test Estimation at all. They want us to start with a Proof of Concept, evaluate based on the results of the PoC and if the results are rosy, go ahead and start the engagement. No clear milestones and deliverables defined, no visibility on resource addition/deletion, no Test Plan/Test strategy identified for the application etc. Terms like Function Points, Testcase Points, Cocomo etc are no more heard in the vicinity.

This trend is definitely not good. Test Managers and Leaders must emphasize the need for estimation and planning to prospects/customers.