This is so spot on!
Supersessionism was first put forward by Justin Martyr and then later picked up by the liberal theological school in Alexandria around 300AD. They expanded this into Amillennialism using a method of interpretation that spiritized Israel to mean the church and allegory to interpret prophecy, rather than stick with literal interpretation first. I'm not sure, but I suspect some of the desire to displace the Jews from God's plan was due to persecution of Christians by Jews in the Apostolic Era and then later during the various persecutions some blame was attached to the Jews for inciting the persecutions.
It's truly ironic that the Jews today distrust Evangelical Christians the most and yet it is Evangelical Christians that rely on literal interpretation and firmly believe the God has a plan for Israel.
Obviously this is a very sensitive topic, but it's importance can't be overstated. Christians are going to have to figure out where they want to stand. For me I'll stand with Israel.
I'll stand with Israel because they are trying to live by God's moral code. For that they get kudos and my hope and prayer is that they will come to know the living Christ. As soon as they start sacrificing their children to Molech again, then I won't.