In the Episcopalian Prayers of the People, Rite I, we pray as follows:
In the communion of [__ and of all the] saints, let us commend ourselves, and one another, and all our life, to Christ our God.
As such, we have at least one Protestant (sort of) group that acknowledges the concept of the communion of the saints. That said, there isn't a lot of understanding of that loaded term.
This term, of course, harkens back to the Apostle's Creed which states:
I believe in the holy catholic church: the communion of saints: the forgiveness of sins, and the life everlasting.
The question, however, is what is the nature of this communion? Is it a fixed gathering of all believers at one time in one place, or is it like an earthly institution, like say, the Boy Scouts, where the membership changes over time, but there is always a membership.