HW failure will tear down the calls anyway, if you rely purely on Ksplice. For telco systems
you need HW redundancy, too. Especially if you are running a commercial network, you had
better not loosing charging data due to HW issues.
Nevertheless, Ksplice alone could help stateless services, like Google's search, where you can
allow data loss due to HW issues. And it can help small systems, too, where HW failure is rare
and less disturbing.
Using Ksplice along with clustering solutions could improve the situation. Keep in mind,
though, that you are just patching the kernel, but the applications remain unfixed. So you did
not end up with a real solution.