The are decommissioning some of the redundant VOR stations. The VOR network will remain operational as a backup to GPS. (See: "VOR minimum operational network")

When it comes to life-critical systems, you never rely on a single point of failure. GPS is potentially a single point of failure. It can and does have errors, either due to military jamming exercises, satellite failures, or other interference. I've personally had the GPS system in my aircraft completely fail due to interference.

It's also worth noting that the FAA considers VOR navigation a required skill. It's part of the core material on the test as a private pilot.