What are some criticisms of contestable markets?

Criticism of contestable markets: 1. No markets 100% contestable (But the market may very well seem “almost contestable” 2. Unrealistic to assume no sunk costs (At least for many industries) 3. No strategic response from incumbent (focus on short run) - Incumbent would price discriminate against entrant to deter hit-and-run 4. Cost is usually not the same for incumbents and entrants (have seen many arguments why it might be higher for entrants)