Without infant Baptism, do Protestants have godparents?
Furthermore, are there any traditions common to most Protestant denominations concerning who should see to it that a child is raised in the Faith in lieu of the parents?
Protestantism is too big and diverse to so make any sweeping statements about it. According to Wikipedia, Lutheran, Anglican, and some Calvinist churches still have godparents. Generally, if a denomination still practices infant baptism, its more likely to also have formalized godparent roles. (Of course, Orthodox and Catholic churches retain the role.)
However, in my experience, most protestant denominations do not regularly include the formal godparent relationship. Once in a while, I've seen family friends stand with the parents at an infant dedication, but it's more of an ad hoc sort of deal. Instead, as I mentioned in a related answer, the entire congregation commits itself to assisting the natural parents in raising children.
But as vsz mentions in the comments:
It depends. In my region most Protestants are Calvinists, and being a godparent is a very important role that binds the two families together, not just an "ad hoc" act.
The Reformation was such a complicated mixture of cultural, religious, intellectual, and national conflicts that making sweeping generalizations rarely covers all the bases.
From the perspective of a parent, I've found that many people in our church have legitimately taken a hand in training our son both spiritually and naturally. And as a member of the congregation, I take my commitment to other people's children seriously whether they have been formally dedicated or not. My wife and I would rather be rebuked for overstepping the boundaries (we have been) than to allow our friend's children to lack outside, Christian, adult interactions.
Many Christian parents organically seek out others who serve many of the same functions of godparents. Some don't. There's a risk of a congregation not responding to cries for help because of the bystander effect and diffusion of responsibility. Perhaps re-instituting the godparent relationship will help.
The purpose of Godparents is to back up the natural parents in raising the child in the Faith should the natural parents die or fail in their duty. This is why, in the Catholic Church, Godparents are not required for an adult who is being Baptized (though they are allowed if the person being Baptized wants it). The the degree that Protestant practices derive from the Catholic practices from which they were "reformed" then absent an authoritative protestant opinion I would (because I am a Catholic and trained in the the teachings of the Catholic Church) defer back to the pre-Protestant practices.