In what sense do you mean?
Just to be clear, I was ambassador in Turkey as well for two years, and was responsible for part of Central Asia as well. Turkey has been a member of the alliance for quite a long time. It is actually an important one. Certainly it was at the time of the Soviet Union, because it was the NATO front line, I guess, with the Soviet Union. It's still a very important ally from a strategic point of view, given what's going on in the Middle East, and given the issues we have fighting Daesh, and it's not over yet, because I think you're going to see some other problems creeping up. Kurds come to mind, for instance.
So Turkey is a critical member of the alliance. It also has—and we saw it in Afghanistan—inroads from an intelligence perspective into some networks that we don't know very well.
The third point I would make is that Turkey is really the only member of NATO that is a Muslim country, and I think that NATO needs at this point to be able to show that it's open to a Muslim country or to Muslim populations in the world. Turkey plays that role.
In terms of what it's bringing to the alliance, I think NATO would lose if Turkey was not a member of the alliance.