Well, it's coming. There will be those 3rd or 4th and ones to stop. I have a formula for stopping this play, which has a 92-93% success rate for the enemy.
The key to the Tush Push is not Hurts. It's not Kelce either. After watching a number of these plays, I notice Hurts more often than not goes left--maybe because Jurgens has been out. The keys to this play are 1. Landon Dickerson, and 2. Jordan Mailata. Hear me out on this.
At the snap of the ball, Dickerson launches himself right into the A gap. He is huge at 6'6", 335. Defenders, who are already low and angled in to pinch the interior gaps, attack immediately, pinching in to the gaps. This is a mistake and the key. Why? Because Mailata, the biggest guy in the league today--he admits that his preferred playing weight is 380, and is 6'8" to boot--crashes into the angled defenders, knocking them away from the point of attack just enough to allow Hurts to ride the wave through. Dickerson created the hole, and Mailata attacks the defenders trying to close the hole.
While I detailed why this isn't a true rugby play, having played both sports, there is an element here that is very important and very rugby-like. If you have ever watched or played rugby, and paid attention to the scrum, you would notice that the players in the scrum and squared up, not angled in. This is important, as squaring up gives the defenders in this formation the best chance to stop momentum. The scrum is all about mass and muscle in a way that is a little bit different then the Tush Push. In rugby, the play doesn't start until the official gives the signal. In our beloved NFL, the offense initiates the play. Once the Tush Push starts, it's mass and muscle.
How to stop this? The defense must be square to the line and attack the player thrusting into the A gap, and also at the same time attack the defender of that player. In other words, attack Landon Dickerson AND Jordan Mailata together. Don't let Mailata wipe out the defenders trying to collapse the interior gaps. Same for the other side if the Eagles go right. Yes, Mailata and Lane Johnson are big, strong as an ox players, but it's really the best chance a defense has to stop this play. Stay square and attack the players defending the initial push into the gap.