GNU Hurd didn't take a good path of development following MACH design. But I still think GNU Hurd is the kernel of the future. Probably the Next generation Hurd. Just because GNU MACH and Hurd present very convoluted designs.
A kernel that performs most of their activities in user space and that it is truly modular looks very promising for the kind of systems we have nowadays and in the future.
Someone has to make the change, or we will stagnate in cumbersome and up featured systems.