With the announcement of the nether update, I have been thinking about the piglin beast specifically. I think that we should be able to tame them so that they are at the very least passive, although I wouldn't be against riding them. I have 2 different ideas on ways to "tame" the piglin beast.
1. Maybe what you could do is hold a specific item in your hand and that would make them passive when you walk past them. Maybe a now nether fruit/vegetable, but I think nether wart would work fine
2. So another ideas is to be able to tame them with trust. Maybe what you could do is feed them to make them passive and then show you don't mean to harm them by say defending them from piglins attack them. I personally like the idea of a trust meter, you could even make it so when they completely tame to you they may still get mad and hit you on occasion.