Pope St John XXIII kisses the feet of a priest at the mandatum
It seems that in order to catch up with his own practice, Pope Francis has changed the rubrics of the Missal to allow those who are to have their feet washed during the Mass of the Lord's Supper to allow candidates to be drawn from all the faithful - ie men or women. See reports: Vatican Bulletin. Catholic Herald.
What a shame it seems to innovate - possibly just to "catch up" with the fact that many parishes have long ignored the prescription of the Missal anyway. It seems so many erosions of the Faith happen this way The rule or instruction is ignored, then comes the legislation to catch up with it because it has already become the accepted practice - the normal, if not the the norm according to the rules. It has been put by many that this is how we ended up with communion in the hand. Surely, legislating to accommodate those who flout the rules is not a good way for any organisation or society to manage itself.
Perhaps it is is another submission to the secular world and the Church being so afraid to be "out of step with it". A sign in itself of a lack of confidence in the whole message of the Faith.
Of course, the instruction does still say that candidates should be drawn from the faithful - that is, from among Catholics...
It also says "can" not "must", so that leaves the door open to continue in the tradition carried on until now.